Thin film transistor, display device, electronic apparatus and method of manufacturing thin film transistor

ABSTRACT

Provided is a thin film transistor, including: a base that includes, on an upper surface, a first region and a second region; a gate electrode that is provided on the first region of the base; a gate insulating film that is provided on a surface of the gate electrode and the second region of the base; and a semiconductor layer that is provided on a surface of the gate insulating film, wherein the semiconductor layer includes a third region and a fourth region, in the third region, the semiconductor layer and the gate electrode face with a minimum interval, in the fourth region, a distance from the semiconductor layer to the gate electrode is larger than the minimum interval, and at a boundary position between the third region and the fourth region, the semiconductor layer forms a linear shape or a substantially linear shape.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of application Ser. No.14/528,620, filed Oct. 30, 2014, and claims the benefit of JapanesePriority Patent Application JP 2013-256582 filed on Dec. 12, 2013, theentire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a thin film transistor that includes aback gate (hereinafter, referred to as a thin film transistor (TFT) of abottom gate type), a display device that includes the thin filmtransistor, an electronic apparatus that includes the display device,and a method of manufacturing the thin film transistor.

A thin film transistor is used as a semiconductor element that controlsa display device such as an organic EL (electroluminescence) displaydevice or a liquid crystal display device. In a thin film transistorthat controls a display device, since a high voltage is applied to adrain, a local concentration of electric field tends to develop in asemiconductor layer in a vicinity of gate edge on the drain side,leading to occurrence of a kink current and degradation in reliability.Therefore, in Japanese Unexamined Patent Application Publication No.2012-109579, the gate and the drain are more spaced to allow alow-concentration impurity region to be implanted between the gate andthe drain, forming an LDD (lightly doped drain).

SUMMARY

However, even such an LDD configuration as in Japanese Unexamined PatentApplication Publication No. 2012-109579 has a disadvantage ofinsufficient relaxing the concentration of electric field in thesemiconductor layer in the vicinity of the gate edge.

It is desirable to provide a thin film transistor that makes it possibleto relax local concentration of electric field in a semiconductor layer,a display device and an electronic apparatus that include the thin filmtransistor, and a method of manufacturing the thin film transistor.

According to an embodiment of the present disclosure, there is provideda thin film transistor including: a base that includes, on an uppersurface, a first region and a second region other than the first region;a gate electrode that is provided on the first region of the base; agate insulating film that is provided on a surface of the gate electrodeand the second region of the base; and a semiconductor layer that isprovided on a surface of the gate insulating film. The semiconductorlayer includes a third region and a fourth region other than the thirdregion. In the third region, the semiconductor layer and the gateelectrode face with a minimum interval. In the fourth region, a distancefrom the semiconductor layer to the gate electrode is larger than theminimum interval. At a boundary position between the third region andthe fourth region, the semiconductor layer forms a linear shape or asubstantially linear shape.

In the thin film transistor according to the above-described embodimentof the present disclosure, at the boundary position between the thirdregion and the fourth region, the semiconductor layer forms a linearshape or a substantially linear shape. Accordingly, at the boundaryposition between the third region and the fourth region, a degree ofbending of a shape of the semiconductor layer is small, allowing agradual change in a distance from the semiconductor layer to the gateelectrode. This leads to a gradual change in a potential in thesemiconductor layer in vicinity of the gate edge, relaxing theconcentration of electric field.

According to an embodiment of the present disclosure, there is provideda display device provided with a display element and a thin filmtransistor that is configured to drive the display element. The thinfilm transistor includes: a base that includes, on an upper surface, afirst region and a second region other than the first region; a gateelectrode that is provided on the first region of the base; a gateinsulating film that is provided on a surface of the gate electrode andthe second region of the base; and a semiconductor layer that isprovided on a surface of the gate insulating film. The semiconductorlayer includes a third region and a fourth region other than the thirdregion. In the third region, the semiconductor layer and the gateelectrode face with a minimum interval. In the fourth region, a distancefrom the semiconductor layer to the gate electrode is larger than theminimum interval. At a boundary position between the third region andthe fourth region, the semiconductor layer forms a linear shape or asubstantially linear shape.

In the display device according to the above-described embodiment of thepresent disclosure, the display element is driven by the thin filmtransistor according to the above-described embodiment of the presentdisclosure, in which the local concentration of electric filed isrelaxed. Accordingly, the occurrence of a kink current or thedegradation in reliability of the thin film transistor is restrained,reducing defects of pixel characteristics and improving display quality.

According to an embodiment of the present disclosure, there is providedan electric apparatus provided with a display device. The display deviceincludes a display element and a thin film transistor that is configuredto drive the display element. The thin film transistor includes: a basethat includes, on an upper surface, a first region and a second regionother than the first region; a gate electrode that is provided on thefirst region of the base; a gate insulating film that is provided on asurface of the gate electrode and the second region of the base; and asemiconductor layer that is provided on a surface of the gate insulatingfilm. The semiconductor layer includes a third region and a fourthregion other than the third region. In the third region, thesemiconductor layer and the gate electrode face with a minimum interval.In the fourth region, a distance from the semiconductor layer to thegate electrode is larger than the minimum interval. At a boundaryposition between the third region and the fourth region, thesemiconductor layer forms a linear shape or a substantially linearshape.

In the electronic apparatus according to the above-described embodimentof the present disclosure, image display is performed by the displaydevice according to the above-described embodiment of the presentdisclosure.

According to an embodiment of the present disclosure, there is provideda method of manufacturing a thin film transistor, the method including:forming a gate electrode on a first region of a base, the baseincluding, on an upper surface, the first region and a second regionother than the first region; forming a gate insulating film on a surfaceof the gate electrode and the second region of the base; and forming asemiconductor layer on a surface of the gate insulating film. Thesemiconductor layer includes a third region and a fourth region otherthan the third region. In the third region, the semiconductor layer andthe gate electrode face with a minimum interval. In the fourth region, adistance from the semiconductor layer to the gate electrode is largerthan the minimum interval. At a boundary position between the thirdregion and the fourth region, the semiconductor layer forms a linearshape or a substantially linear shape.

According to the thin film transistor, the display device, theelectronic apparatus, and the method of manufacturing the thin filmtransistor in the above-described embodiments of the present disclosure,at the boundary position between the third region and the fourth region,the semiconductor layer forms a linear shape or a substantially linearshape. Hence, it is possible, at the boundary position between the thirdregion and the fourth region, to allow a gradual change in a distancefrom the semiconductor layer to the gate electrode, relaxing the localconcentration of electric field in the semiconductor layer.

It is to be noted that some effects described here are not necessarilylimitative, and any of other effects described herein may be achieved.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a cross-sectional view illustrating a configuration of a thinfilm transistor according to a reference example 1.

FIG. 2 is a cross-sectional view illustrating, in an enlarged manner, apart of the thin film transistor according to the reference example 1.

FIG. 3 is a diagram illustrating an Id-Vd curve of the thin filmtransistor illustrated in FIG. 1.

FIG. 4 is a cross-sectional view illustrating a configuration of a thinfilm transistor according to a first embodiment of the presentdisclosure.

FIG. 5 is a cross-sectional view illustrating, in an enlarged manner, apart of the thin film transistor illustrated in FIG. 4.

FIG. 6 is a cross-sectional view illustrating a method of manufacturingthe thin film transistor illustrated in FIG. 4 in the order ofprocedure.

FIG. 7 is a cross-sectional view illustrating a process following FIG.6.

FIG. 8 is a cross-sectional view illustrating a process following FIG.7.

FIG. 9 is a cross-sectional view illustrating a process following FIG.8.

FIG. 10 is a cross-sectional view illustrating a process following FIG.9.

FIG. 11 is a cross-sectional view illustrating a process following FIG.10.

FIG. 12 is a cross-sectional view illustrating a process following FIG.11.

FIG. 13 is a cross-sectional view illustrating a process following FIG.12.

FIG. 14 is a diagram illustrating an Id-Vd curve of the thin filmtransistor illustrated in FIG. 4 in comparison with the referenceexample 1.

FIG. 15 is a cross-sectional view illustrating a configuration of a thinfilm transistor according to a modification example 1.

FIG. 16 is a cross-sectional view illustrating a process in a method ofmanufacturing a thin film transistor according to a modification example2.

FIG. 17 is a cross-sectional view illustrating a configuration of a thinfilm transistor according to a second embodiment of the presentdisclosure.

FIG. 18 is a cross-sectional view illustrating a method of manufacturingthe thin film transistor illustrated in FIG. 17 in the order ofprocedures.

FIG. 19 is a cross-sectional view illustrating a process following FIG.18.

FIG. 20 is a cross-sectional view illustrating a process following FIG.19.

FIG. 21 is a cross-sectional view illustrating a process following FIG.20.

FIG. 22 is a cross-sectional view illustrating a process following FIG.21.

FIG. 23 is a cross-sectional view illustrating a process following FIG.22.

FIG. 24 is a cross-sectional view illustrating a process following FIG.23.

FIG. 25 is a cross-sectional view illustrating a process following FIG.24.

FIG. 26 is a cross-sectional view illustrating a process following FIG.25.

FIG. 27 is a cross-sectional view illustrating a configuration of a thinfilm transistor according to a third embodiment of the presentdisclosure.

FIG. 28 is a cross-sectional view illustrating, in an enlarged manner, apart of the thin film transistor illustrated in FIG. 27.

FIG. 29 is a cross-sectional view illustrating a method of manufacturingthe thin film transistor illustrated in FIG. 27 in the order ofprocedure.

FIG. 30 is a cross-sectional view illustrating a process following FIG.29.

FIG. 31 is a cross-sectional view illustrating a process following FIG.30.

FIG. 32 is a cross-sectional view illustrating a process following FIG.31.

FIG. 33 is a cross-sectional view illustrating a process following FIG.32.

FIG. 34 is a cross-sectional view illustrating a process following FIG.33.

FIG. 35 is a cross-sectional view illustrating a process following FIG.34.

FIG. 36 is a cross-sectional view illustrating a process following FIG.35.

FIG. 37 is a diagram illustrating an Id-Vd curve of the thin filmtransistor illustrated in FIG. 36 in comparison with the referenceexample 1.

FIG. 38 is a cross-sectional view illustrating a configuration of a thinfilm transistor according to a fourth embodiment of the presentdisclosure.

FIG. 39 is a cross-sectional view illustrating, in an enlarged manner, apart of the thin film transistor illustrated in FIG. 38.

FIG. 40 is a cross-sectional view illustrating a method of manufacturingthe thin film transistor illustrated in FIG. 38 in the order ofprocedure.

FIG. 41 is a cross-sectional view illustrating a process following FIG.40.

FIG. 42 is a cross-sectional view illustrating a process following FIG.41.

FIG. 43 is a cross-sectional view illustrating a process following FIG.42.

FIG. 44 is a cross-sectional view illustrating a process following FIG.43.

FIG. 45 is a cross-sectional view illustrating a process following FIG.44.

FIG. 46 is a cross-sectional view illustrating a process following FIG.45.

FIG. 47 is a cross-sectional view illustrating a process following FIG.46.

FIG. 48 is a diagram illustrating an Id-Vd curve of the thin filmtransistor illustrated in FIG. 38 in comparison with the referenceexample 1.

FIG. 49 is a block diagram illustrating an overall configuration of adisplay device according to a fifth embodiment of the presentdisclosure.

FIG. 50 is a diagram illustrating one example of a pixel circuit of thedisplay device illustrated in FIG. 49.

FIG. 51 is a cross-sectional view illustrating a configuration of thepixel illustrated in FIG. 50.

FIG. 52 is a cross-sectional view illustrating one example of an organiclayer illustrated in FIG. 51.

FIG. 53 is a cross-sectional view illustrating another example of theorganic layer illustrated in FIG. 51.

FIG. 54 is a cross-sectional view illustrating still another example ofthe organic layer illustrated in FIG. 51.

FIG. 55 is a cross-sectional view illustrating a configuration of apixel of a display device according to a modification example 3 of thepresent disclosure.

FIG. 56 is a plan view illustrating a configuration of anelectrophoretic element as an example of a display element, in a displaydevice according to a modification example 4 of the present disclosure.

FIG. 57 is a cross-sectional view illustrating a configuration of theelectrophoretic element illustrated in FIG. 56.

FIG. 58 is a cross-sectional view illustrating a configuration of apixel of a display device including the electrophoretic elementillustrated in FIG. 57.

FIG. 59 is a cross-sectional view illustrating an operation of thedisplay device illustrated in FIG. 58.

FIG. 60 is a plan view illustrating an overall configuration of a moduleincluding the display device of the above-described embodiment.

FIG. 61 is a perspective view illustrating an appearance of anapplication example 1.

FIG. 62 is another perspective view illustrating the appearance of theapplication example 1.

FIG. 63 is a perspective view illustrating an appearance of anapplication example 2 viewed from the front side.

FIG. 64 is a perspective view illustrating the appearance of theapplication example 2 viewed from the back side.

FIG. 65 is a perspective view illustrating an appearance of anapplication example 3.

FIG. 66 is a perspective view illustrating an appearance of anapplication example 4.

FIG. 67 is a perspective view illustrating an appearance of anapplication example 5 viewed from the front side.

FIG. 68 is a perspective view illustrating the appearance of theapplication example 5 viewed from the back side.

FIG. 69 is a perspective view illustrating an appearance of theapplication example 6.

FIG. 70 is a perspective view illustrating an appearance of theapplication example 7.

FIG. 71 is a perspective view illustrating an application example 8 inan opened state.

FIG. 72 is a perspective view illustrating the application example 8 ina closed state.

FIG. 73 illustrates an application example 9 in a closed state.

FIG. 74 illustrates the application example 9 in an opened state.

DETAILED DESCRIPTION

In the following, some embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. It isto be noted that description will be made in the following order.

1. Reference Example 1

2. First Embodiment (thin film transistor; one example in which a fifthregion and a sixth region are provided in a second region on a sourceside and on a drain side of a base)

3. Modification Example 1 (thin film transistor; one example in whichthe fifth region and the sixth region are provided in the second regionon the drain side of the base)

4. Modification Example 2 (method of manufacturing thin film transistor;one example in which, in etching the second region of the base, a maskof a same layout as that of a gate electrode is used)

5. Second Embodiment (thin film transistor; one example in which thebase is configured of a laminated body of a first insulating layer and asecond insulating layer)

6. Third Embodiment (thin film transistor; one example in which an uppersurface of a gate insulating film is flat)

7. Fourth Embodiment (thin film transistor; one example in which a sidewall is attached to a side surface of the gate electrode)

8. Fifth Embodiment (organic EL display device)

9. Modification Example 3 (liquid crystal display device)

10. Modification Example 4 (electronic paper display device)

11. Application Examples (module and electronic apparatuses)

Reference Example 1

First, prior to description of specific example embodiments, as anassumption that is a base of the present disclosure and is common to thespecific example embodiments, description will be given, with referenceto experiment results, on a local concentration of electric field in asemiconductor layer in a vicinity of a gate edge.

FIG. 1 illustrates a cross-sectional configuration of a thin filmtransistor 10R according to a reference example 1. The thin filmtransistor 10R according to the reference example 1 is a TFT of a bottomgate type, and includes, for example, on a flat surface of a base 11, agate electrode 12, a gate insulating film 13, a semiconductor layer 14,an insulating film (a protective film) 15, a source electrode 16S, and adrain electrode 16D in this order.

The base 11 is configured of a glass substrate. The gate electrode 12 isconfigured of, for example, molybdenum (Mo). The gate insulating film 13is configured of a layered film of a silicon nitride film (Si₃N₄) and asilicon oxide film (SiO₂). The semiconductor layer 14 is configured ofpolysilicon. The insulating film 15 is configured of a layered film of asilicon oxide film and a silicon nitride film. It is to be noted that anLDD (not illustrated) is provided at a gate edge of the semiconductorlayer 14.

In the thin film transistor 10R, on the flat base 11, the gate electrode12 is patterned. On the base 11 and the gate electrode 12, the gateinsulating film 13 and the semiconductor layer 14 are provided. Thesemiconductor layer 14 bends in shape along a level difference due tothe gate electrode 12. A bottom surface of a portion in which thesemiconductor layer 14 does not rise up on the gate electrode 12 ispositioned higher than the position of an upper surface of the base 11by a thickness of the gate insulating film 13. In other words, adifference between a portion in which the semiconductor layer 14 risesup on the gate electrode 12 and the portion in which the semiconductorlayer 14 does not rise up on the gate electrode 12 is equal to athickness of the gate electrode 12.

In the configuration of the reference example 1, as illustrated in FIG.2, at an edge of the gate electrode 12, there is a sudden increase in adistance D from the semiconductor layer 14 to the gate electrode 12,causing a steep potential change. This leads to an increase in anelectric field, also affected by the bending shape of the semiconductorlayer 14. That is, a position P1 of the sudden increase in the distanceD from the semiconductor layer 14 to the gate electrode 12 coincideswith a position P2 where the semiconductor layer 14 bends in shape,involving occurrence of a concentration FC of electric field at the edgeof the gate electrode 12, as illustrated in FIG. 1. Thus, impactionization occurs, causing occurrence of a kink K1 as illustrated inFIG. 3 or degradation in reliability.

In other words, by allowing the position P1 of the sudden increase inthe distance D from the semiconductor layer 14 to the gate electrode 12to be different from the position P2 where the semiconductor layer 14bends in shape, it is possible to allow the distance D to changegradually, relaxing the concentration of electric field and restrainingthe kink K1 due to the concentration of electric field.

In the following, description will be given, based on the result of thereference example 1 as described above, on specific example embodiments(first to fourth embodiments).

First Embodiment

FIG. 4 illustrates a cross-sectional configuration of a thin filmtransistor according to a first embodiment of the present disclosure.The thin film transistor 10 may be used in an active matrix drivecircuit of a display device such as an organic EL display device or aliquid crystal display device. The thin film transistor 10 is, forexample, a TFT of a bottom gate type, and includes, on the base 11, thegate electrode 12, the gate insulating film 13, the semiconductor layer14, the insulating film (the protective film) 15, the source electrode16S, and the drain electrode 16D.

The base 11 includes, on an upper surface, a first region A1 and asecond region A2 other than the first region A1. The first region A1 isa flat region on which the gate electrode 12 is provided. The gateinsulating film 13 is provided on a surface (an upper surface 12A andside surfaces 12B) of the gate electrode 12 and the second region A2 ofthe base 11. The semiconductor layer 14 is provided on a surface of thegate insulating film 13.

In the thin film transistor 10, an upper surface of the first region A1beneath the gate electrode 12 is positioned at a higher level than anupper surface of the second region A2 other than the first region A1. Onthe surface of gate electrode 12 and the second region A2 of the base11, the gate insulating film 13 and the semiconductor layer 14 areprovided. Thus, the difference between the portion in which thesemiconductor layer 14 rises up on the gate electrode 12 and the portionin which the semiconductor layer 14 does not rise up on the gateelectrode 12 is larger than the thickness of the gate electrode 12.Accordingly, as illustrated in FIG. 5 in an enlarged manner, at the edgeof the gate electrode 12, there is a more gradual change in thedifference D from the semiconductor layer 14 to the gate electrode 12 ascompared to the reference example 1, causing a gradual potential change.That is, the position P1 where the distance D from the semiconductorlayer 14 to the gate electrode 12 changes does not coincide with theposition P2 where the semiconductor layer 14 bends in shape. This makesit possible to relax the concentration of the electric field at the edgeof the gate electrode 12.

In other words, the semiconductor layer 14 includes a third region A3and a fourth region A4 other than the third region A3. In the thirdregion A3, the semiconductor layer 14 and the gate electrode 12 facewith a minimum interval (i.e. a length of a perpendicular drawn downfrom a point of a bottom surface of the semiconductor layer 14 to thegate electrode 12, or a thickness of a gate insulating film 13). In thefourth region A4, the distance D from the semiconductor layer 14 to thegate electrode 12 is larger than the minimum interval. At a boundaryposition P1 between the third region A3 and the fourth region A4, thesemiconductor layer 14 forms a linear shape or a substantially linearshape. Thus, in the display device 10, it is possible to relax the localconcentration of electric field in the semiconductor layer 14. It is tobe noted that “a linear shape or a substantially linear shape” includesnot only a line as geometrically defined but also what may be calledsubstantially a line in consideration of processing precision in amanufacturing procedure.

Moreover, the base 11 includes, in the second region A2, a fifth regionA5 and a sixth region A6. The fifth region A5 is inclined with respectto the first region A1. The sixth region A6 is parallel to the firstregion A1, that is, a flat region. The boundary position P1 between thethird region A3 and the fourth region A4 of the semiconductor layer 14is different from the position P2 where the semiconductor layer 14 bendsin shape at a boundary between the fifth region A5 and the sixth regionA6 of the base 11. In this way, the degree of bending of the shape ofthe semiconductor layer 14 becomes small, causing a more gradual changein the distance D from the semiconductor layer 14 to the gate electrode12 as compared to the reference example 1. As a result, it is possibleto relax the concentration of electric field and to restrain a kink dueto the concentration of electric field. A level difference Δh betweenthe first region A1 and the sixth region A6 of the base 11 maypreferably be larger than the thickness of the gate electrode 12.

Furthermore, the gate electrode 12 includes an upper surface 12A andside surfaces 12B. The upper surface 12A is parallel to the first regionA1. The side surfaces 12B are inclined with respect to the first regionA1. The side surface 12B of the gate electrode 12 and the fifth regionA5 form a linear shape or a substantially linear shape. In this way, itis possible to reduce the degree of bending in shape of thesemiconductor layer 14 at the boundary position P1, allowing the changein the distance D at the boundary position P1 to be more gradual.

Materials of the respective layers of the thin film transistor 10 are asfollows.

The base 11 is configured of, for example, an insulating substrate suchas a glass substrate. The base 11 may be a plastic film or a metalsubstrate such as stainless steel (SUS) depending on purposes. Examplesof plastic materials may include polyethylene telephthalate (PET) andpolyethylene naphthalate (PEN).

The gate electrode 12 is adapted to control a carrier density (anelectron density as exemplified) in the semiconductor layer 14 accordingto a gate voltage applied to the thin film transistor 10. The gateelectrode 12 may be configured of, for example, a single layer film ofone of low resistance metals such as aluminum (Al) and copper (Cu),titanium (Ti), and molybdenum (Mo), and so on. The gate electrode 12 maybe configured of a layered film of two or more of the above-mentionedmaterials.

The gate insulating film 13 and the insulating film 15 may be configuredof a single layer film or a layered film of a silicon oxide film, asilicon nitride film, a silicon oxide nitride film, an aluminum oxidefilm, and so on.

The semiconductor layer 14 is provided, on the gate insulating film 13,in an island form that includes the gate electrode 12 and theneighborhood of the gate electrode 12. The semiconductor layer 14 has afunction of an active layer of the thin film transistor 10. Thesemiconductor layer 14 may be configured of amorphous silicon,crystalline silicon (for example, polysilicon), an oxide semiconductor,an organic semiconductor, and so on. An oxide semiconductor refers to acompound that includes an element or elements such as indium, gallium,zinc, and tin, and oxygen. Specifically, examples of amorphous oxidesemiconductors may include indium gallium zinc oxide (IGZO) and indiumtin zinc oxide (ITZO), and so on. Examples of crystalline oxidesemiconductors may include zinc oxide (ZnO), indium zinc oxide (IZO (aregistered trademark)), indium gallium oxide (IGO), indium tin oxide(ITO), indium oxide (InO), and so on. Examples of organic semiconductorsmay include peri-xanthenoxanthene (PXX) derivatives, pentacene (C₂₂H₁₄),polythiophene, and so on.

The source electrode 16S and the drain electrode 16D may be configuredof, for example, a single layer film of one of low resistance metalssuch as aluminum (Al) and copper (Cu), titanium (Ti), and molybdenum(Mo), and so on. The source electrode 16S and the drain electrode 16Dmay be configured of a layered film of two or more of theabove-mentioned materials. The source electrode 16S and the drainelectrode 16D are connected to the semiconductor layer 14 throughcontact holes H1 that are provided in the insulating film 15.

The thin film transistor 10 may be manufactured, for example, asfollows.

FIGS. 6 to 13 illustrate a method of manufacturing the thin filmtransistor 10 in the order of procedure. First, as illustrated in FIG.6, the base 11 that is configured of, for example, a glass substrate isprepared. On the base 11, a gate electrode material film (notillustrated) that is configured of, for example, molybdenum is formedby, for example, a sputtering method. Next, the gate electrode materialfilm is subjected to photolithography and etching. Thus, as illustratedin FIG. 7, the gate electrode 12 is patterned in the first region A1 ofthe base 11.

Subsequently, as illustrated in FIG. 8, the second region A2 of the base11 is etched with the gate electrode 12 as a mask. Thus, in the secondregion A2 of the base 11, the fifth region A5 and the sixth region A6are formed. The fifth region A5 is inclined with respect to the firstregion A1. The sixth region A6 is parallel to the first region A1. Ataper angle in etching the base 11 may be desirably same as a taperangle of the side surface 12B of the gate electrode 12; the side surface12B of the gate electrode 12 and the fifth region A5 may desirably forma linear shape or a substantially linear shape; but this is notlimitative. Moreover, the second region A2 of the base 11 may bepreferably etched deeper than the thickness of the gate electrode 12.Thus, it is possible to allow the level difference Δh (FIG. 4) betweenthe first region A1 and the sixth region A6 to be larger than thethickness of the gate electrode 12.

After this, as illustrated in FIG. 9, on the surface of the gateelectrode 12 and the second region A2 of the base 11, the gateinsulating film 13 is formed by, for example, a chemical vapordeposition (CVD) method. The gate insulating film 13 may be configuredof, for example, a layered film of a silicon nitride film and a siliconoxide film. The gate insulating film 13 may be preferably formed with auniform thickness.

After forming the gate insulating film 13, on the surface of the gateinsulating film 13, a semiconductor material film (not illustrated),which is configured of the above-mentioned material, specificallypolysilicon, is formed. The semiconductor material film is patterned toa predetermined shape by, for example, photolithography and etching.Thus, as illustrated in FIG. 10, the semiconductor layer 14 is formed.The semiconductor flayer 14 may be preferably formed with a uniformthickness.

After forming the semiconductor layer 14, as illustrated in FIG. 11, onthe surface of the semiconductor layer 14, the insulating film 15 isformed by, for example, a CVD method. The insulating film 15 may beconfigured of a layered film of a silicon oxide film and a siliconnitride film.

After forming the insulating film 15, as illustrated in FIG. 12, a maskM1, which is configured of a resist film, is formed on the insulatingfilm 15. By etching with the use of the mask M1, the contact holes H1are formed in the insulating film 15. Subsequently, as illustrated inFIG. 13, the source electrode 16S and the drain electrode 16D areformed. The source electrode 16S and the drain electrode 16D areconnected to the semiconductor layer 14 through the contact holes H1.Thus, the thin film transistor 10 as illustrated in FIG. 4 is completed.

FIG. 14 illustrates an Id-Vd characteristic of the thin film transistor10. It is to be noted that the FIG. 14 also illustrates the result ofthe reference example 1 as well.

As seen from FIG. 14, in the thin film transistor 10 according to thepresent embodiment, an amount of kink occurring is reduced as comparedto the reference example 1. A possible reason may be as follows. In thepresent embodiment, the position P1 of the change in the distance D fromthe semiconductor layer 14 to the gate electrode 12 is apart from theposition P2 where the semiconductor layer 14 bends in shape. This allowsa gradual change in the distance D, relaxing the concentration ofelectric field at the edge of the gate electrode 12. That is, it isknown that if the semiconductor layer 14 forms a linear shape or asubstantially linear shape at the boundary position P1 between the thirdregion A3 and the fourth region A4 of the semiconductor layer 14, it ispossible to relax the local concentration of electric field in thesemiconductor layer 14.

As described above, in the present embodiment, the semiconductor layer14 forms a linear shape or a substantially linear shape at the boundaryposition P1 between the third region A3 and the fourth region A4 of thesemiconductor layer 14. Hence, it is possible to reduce the degree ofbending of the shape of the semiconductor layer 14, allowing thedistance D from the semiconductor layer 14 to the gate electrode 12 tochange gradually and relaxing the local concentration of electric filedin the semiconductor layer 14.

In particular, in the second region A2 of the base 11, the fifth regionA5 and the sixth region A6 are formed. The fifth region A5 is inclinedwith respect to the first region A1. The sixth region A6 is parallel tothe first region A1. The boundary position P1 between the third regionA3 and the fourth region A4 of the semiconductor layer 14 is differentfrom the position P2 where the semiconductor layer 14 bends in shape atthe boundary between the fifth region A5 and the sixth region A6. Hence,it is possible to reduce the degree of bending of the shape of thesemiconductor layer 14 at the boundary position P1, allowing thedistance D to change more gradually.

Modification Example 1

In the above-described first embodiment, description has been given on acase that the fifth region A5 is provided both on the source side and onthe drain side of the gate electrode 12. However, as illustrated in FIG.15, the fifth region A5 may be provided on the drain side of the gateelectrode 12. In the thin film transistor 10 that drives a displaydevice, since a high voltage is applied to the drain, the concentrationof electric field is likely to occur on the drain side of the gateelectrode 12 in particular. By providing the fifth region A5 on thedrain side of the gate electrode 12, it is possible to relax theconcentration of electric field occurring on the drain side.

Modification Example 2

Moreover, in the above-described first embodiment, description has beengiven on a case that, in etching the second region A2 of the base 11,the gate electrode 12 is used as a mask. However, as illustrated in FIG.16, in etching the second region A2 of the base 11, a resist film havinga same layout as the gate electrode 12 may be used as a mask M2.

Second Embodiment

FIG. 17 illustrates a cross-sectional configuration of a thin filmtransistor 10A according to a second embodiment of the presentdisclosure. The thin film transistor 10A according to the presentembodiment is provided with an insulating layer that is separate from aglass substrate, in a portion of the base 11 beneath the gate electrode12. Otherwise, configurations, functions, and effects are similar tothose of the thin film transistor 10 according to the above-describedfirst embodiment. Thus, description will be given with similarcomponents denoted by similar reference numerals.

The base 11 is configured of a laminated body of a first insulatinglayer 11A and a second insulating layer 11B. The first insulating layer11A serves as a support of the whole thin film transistor 10A, and maybe configured of, for example, a glass substrate. The second insulatinglayer 11B is provided in a region beneath the gate electrode 12, and maybe configured of, for example, a single layer film or a layered film ofa silicon oxide film, a silicon nitride film, a silicon nitride oxidefilm, an aluminum oxide film, and so on. That is, the first region A1 ofthe base 11 has a configuration in which the second insulating layer 11Bis laminated on the first insulating layer 11A. The fifth region A5 isconfigured of a side surface of the second insulating layer 11B. Thesixth region A6 is configured of an upper surface of the firstinsulating layer 11A.

The thin film transistor 10A may be manufactured, for example, asfollows.

FIGS. 18 to 26 illustrate a method of manufacturing the thin filmtransistor 10A in the order of procedure. First, as illustrated in FIG.18, the first insulating layer 11A that is configured of, for example, aglass substrate is prepared. On the first insulating layer 11A, thesecond insulating layer 11B is formed. Thus, as illustrated in FIG. 19,the base 11 that is configured of a laminated body of the firstinsulating layer 11A and the second insulating layer 11B is formed.

Next, as illustrated in FIG. 20, on the second insulating layer 11B ofthe base 11, a gate electrode material film 12C that is configured of,for example, a metal such as molybdenum is formed by, for example, asputtering method.

Subsequently, the gate electrode material film 12C is subjected tophotolithography and etching. Thus, as illustrated in FIG. 21, the gateelectrode 12 is patterned in the first region A1 of the base 11.

Furthermore, as illustrated in FIG. 21 as well, the second region A2 ofthe base 11 is etched using, as a mask, the gate electrode 12 or aresist film (not illustrated) having a same layout as the gate electrode12. Thus, in the second region A2 of the base 11, the fifth region A5and the sixth region A6 are formed. The fifth region A5 is inclined withrespect to the first region A1. The sixth region A6 is parallel to thefirst region A1. The first region A1 has a configuration in which thesecond insulating layer 11B is laminated on the first insulating layer11A. The fifth region A5 is configured of the side surface of the secondinsulating layer 11B. The sixth region A6 is configured of the uppersurface of the first insulating layer 11A. The taper angle in etchingthe base 11 may be desirably same as the taper angle of the side surface12B of the gate electrode 12; the side surface 12B of the gate electrode12 and the fifth region A5 may desirably form a linear shape or asubstantially linear shape; but this is not limitative.

After this, as illustrated in FIG. 22, on the surface of the gateelectrode 12 and the second region A2 of the base 11, the gateinsulating film 13 is formed by, for example, a CVD method. The gateinsulating film 13 may be configured of, for example, a layered film ofa silicon nitride film and a silicon oxide film. The gate insulatingfilm 13 may be preferably formed with a uniform thickness.

After forming the gate insulating film 13, on the surface of the gateinsulating film 13, a semiconductor material film (not illustrated),which is configured of the above-mentioned material, specificallypolysilicon, is formed. The semiconductor material film is patterned toa predetermined shape by, for example, photolithography and etching.Thus, as illustrated in FIG. 23, the semiconductor layer 14 is formed.The semiconductor layer 14 may be preferably formed with a uniformthickness.

After forming the semiconductor layer 14, as illustrated in FIG. 24, onthe surface of the semiconductor layer 14, the insulating film 15 isformed by, for example, a CVD method. The insulating film 15 may beconfigured of a layered film of a silicon oxide film and a siliconnitride film.

After forming the insulating film 15, as illustrated in FIG. 25, a maskM1, which is configured of a resist film, is formed on the insulatingfilm 15. By etching with the use of the mask M1, the contact holes H1are formed in the insulating film 15. Subsequently, as illustrated inFIG. 26, the source electrode 16S and the drain electrode 16D areformed. The source electrode 16S and the drain electrode 16D areconnected to the semiconductor layer 14 through the contact holes H1.Thus, the thin film transistor 10A as illustrated in FIG. 17 iscompleted.

The Id-Vd characteristic of the thin film transistor 10A is similar tothe description in the first embodiment with reference to the FIG. 14.

As described above, in the present embodiment, in addition to effects ofthe above-described first embodiment, it is possible to obtain thefollowing effects. The first region A1 of the base 11 is a laminatedbody in which the second insulating layer 11B is laminated on the firstinsulating layer 11A. The fifth region A5 is configured of the sidesurface of the second insulating layer 11B. The sixth region A6 isconfigured of the upper surface of the first insulating layer 11A.Hence, it is possible to form the fifth region A5 easily and with highprecision.

Third Embodiment

FIG. 27 illustrates a cross-sectional configuration of the thin filmtransistor 10B according to a third embodiment of the presentembodiment. In the thin film transistor 10B according to the presentembodiment, the semiconductor layer 14 has a linear shape with littlelevel difference. Otherwise, configurations, functions, and effects aresimilar to those of the thin film transistor 10 according to theabove-described first embodiment. Thus, description will be given withsimilar components denoted by similar reference numerals.

In the thin film transistor 10B, there is provided a spacer layer 18 inthe second region A2 of the base 11, allowing the surface 13A (alsoreferred to as the upper surface 13A in the followings) of the gateinsulating film 13 to be flat. The semiconductor layer 14 is formed in alinear shape parallel to the first region A1. That is, the semiconductorlayer 14 is formed as a flat layer. Thus, as illustrated in FIG. 28 inan enlarged manner, there is no position P2 where the semiconductorlayer 14 bends in shape. This allows a gradual change in the distance Dfrom the semiconductor layer 14 to the gate electrode 12 at the boundaryposition P1 between the third region A3 and the fourth region A4, makingit possible to relax the local concentration of electric field in thesemiconductor layer 14.

Here, a surface may be sufficiently described “flat” if unevenness ofthe surface is smaller than the thickness of the gate electrode 12.Also, a layer may be described “flat” if both an upper surface and alower surface of the layer satisfy the above-mentioned definition offlatness of a surface.

The spacer layer 18 is adapted to eliminate or relax a level differencedue to the thickness of the gate electrode 12, allowing the uppersurface 13A of the gate insulating film 13 to be flat. The spacer layer18 is provided in the second region A2 of the base 11, and has athickness that is equal to or substantially equal to the thickness ofthe gate electrode 12. An upper surface 18A of the spacer layer 18 formsa linear shape or a substantially linear shape that is continuous withthe upper surface 12A of the gate electrode 12, forming a parallelsurface to the first region A1.

The spacer layer 18 may be configured of, for example, a single layerfilm or a layered film of a resin, a silicon oxide film, a siliconnitride film, a silicon nitride oxide film, or an aluminum oxide film,or the like.

The thin film transistor 10B may be manufactured, for example, asfollows.

FIGS. 29 to 36 illustrate a method of manufacturing the thin filmtransistor 10B in the order of procedure. First, as illustrated in FIG.29, the base 11 that is configured of, for example, a glass substrate isprepared. As illustrated in FIG. 30, on the base 11, a spacer materialfilm 18B, which is configured of a resin, or an oxide film, or the likeas mentioned above, is formed.

Next, using photolithography, on the spacer material film 18B, a resistpattern (not illustrated) is formed. By etching with the resist patternas a mask, a part of the spacer material film 18B is removed to form anopening 18C, in which the base 11 is exposed. Thus, as illustrated inFIG. 31, the spacer layer 18 is formed.

Subsequently, in the opening 18C of the spacer layer 18, a material ofthe gate electrode 12, specifically molybdenum, is vapor-deposited.Alternatively, over the spacer layer 18 and in the opening 18C, a gateelectrode material film (not illustrated), which is configured of, forexample, molybdenum, is formed by, for example, a sputtering method, andthen the gate electrode material film is etched back. Thus, asillustrated in FIG. 32, the gate electrode 12 is formed in the firstregion A1 of the base 11, while the spacer layer 18 is formed in thesecond region A2 of the base 11. The spacer layer 18 has a thicknessthat is same or substantially same as the thickness of the gateelectrode 12. The upper surface 18A of the spacer layer 18 forms alinear shape or a substantially linear shape that is continuous with theupper surface 12A of the gate electrode 12.

After this, as illustrated in FIG. 33, on the upper surface 12A of thegate electrode 12 and the upper surface 18A of the spacer layer 18, thegate insulating film 13 is formed by, for example, a CVD method. Thegate insulating film 13 may be configured of, for example, a layeredfilm of a silicon nitride film and a silicon oxide film. Thus, the gateinsulating film 13 having the flat upper surface 13A is formed. The gateinsulating film 13 may be preferably formed with a uniform thickness.

After forming the gate insulating film 13, on the flat surface 13A ofthe gate insulating film 13, a semiconductor material film (notillustrated), which is formed of the above-mentioned material,specifically polysilicon, is formed. The semiconductor material film ispatterned to a predetermined shape by, for example, photolithography andetching. Thus, as illustrated in FIG. 34, the semiconductor layer 14 asa flat layer is formed on the flat surface 13A of the gate insulatingfilm 13. The semiconductor layer 14 may be preferably formed with auniform thickness.

After forming the semiconductor layer 14, as illustrated in FIG. 35, onthe surface of the semiconductor layer 14, the insulating film 15 isformed by, for example, a CVD method. The insulating film 15 may beconfigured of a layered film of a silicon oxide film and a siliconnitride film.

After forming the insulating film 15, as illustrated in FIG. 36, thecontact holes H1 are formed in the insulating film 15. Subsequently, asillustrated in FIG. 27, the source electrode 16S and the drain electrode16D are formed. The source electrode 16S and the drain electrode 16D areconnected to the semiconductor layer 14 through the contact holes H1.Thus, the thin film transistor 10B as illustrated in FIG. 27 iscompleted.

FIG. 37 illustrates an Id-Vd characteristic of the thin film transistor10B. It is to be noted that FIG. 37 also illustrates the result of thereference example 1 as well.

As seen from FIG. 37, in the thin film transistor 10B according to thepresent embodiment, an amount of kink occurring is reduced as comparedto the reference example 1. A possible reason may be as follows. Theposition P1 of the change in the distance D from the semiconductor layer14 to the gate electrode 12 is apart from the position P2 where thesemiconductor layer 14 bends in shape. This allows a gradual change inthe distance D, relaxing the concentration of electric field at the edgeof the gate electrode 12. That is, it is known that if the semiconductorlayer 14 forms a linear shape that is parallel to the first region A1,it is possible to relax the local concentration of electric field in thesemiconductor layer 14.

As described above, in the present embodiment, the semiconductor layer14 has a linear shape that is parallel to the first region A1. Hence, itis possible to reduce the degree of bending of the shape of thesemiconductor layer 14 at the boundary position P1. This allows agradual change in the distance D from the semiconductor layer 14 to thegate electrode 12, relaxing the local concentration of electric field inthe semiconductor layer 14.

Fourth Embodiment

FIG. 38 illustrates a cross-sectional configuration of a thin filmtransistor 10C according to a fourth embodiment of the presentdisclosure. The present embodiment involves a side wall SW that isprovided on the side surface 12B of the gate electrode 12, allowing agradual change in the distance D from the semiconductor layer 14 to thegate electrode 12. Otherwise, the thin film transistor 10C according tothe present embodiment has similar configurations, functions, andeffects to those of the thin film transistor 10 according to theabove-described first embodiment. Therefore, description will be givenwith similar components denoted by similar reference numerals.

In the thin film transistor 10C, since the side wall SW is provided onthe side surface 12B of the gate electrode 12, a degree of inclinationof the semiconductor layer 14 with respect to the first region A1 at theside surface 12B of the gate electrode 12 is different from a degree ofinclination of the side surface 12B of the gate electrode 12 withrespect to the first region A1. Also in this case, as illustrated inFIG. 39 in an enlarged manner, the position P1 of the change in thedistance D from the semiconductor layer 14 to the gate electrode 12 doesnot coincide with the position P2 where the semiconductor layer 14 bendsin shape, making it possible to relax the concentration of electricfield at the edge of the gate electrode 12. In other words, it ispossible to reduce the degree of bending of the shape of thesemiconductor layer 14 at the boundary position P1. This allows agradual change in the distance D from the semiconductor layer 14 to thegate electrode 12, relaxing the local concentration of electric field inthe semiconductor layer 14.

The side wall SW may have a triangular shape in section that is narrowedin width from the bottom (the base 11 side) toward the top along theside surface 12B of the gate electrode 12. The side wall SW may beconfigured of, for example, a silicon nitride film.

The thin film transistor 10C may be manufactured, for example, asfollows.

FIGS. 40 to 47 illustrate a method of manufacturing the thin filmtransistor 10C in the order of procedure. First, as illustrated in FIG.40, the base 11 that is configured of, for example, a glass substrate isprepared. On the base 11, a gate electrode material film (notillustrated) that is configured of, for example, molybdenum is formedby, for example, a sputtering method. Next, the gate electrode materialfilm is subjected to photolithography and etching. Thus, as illustratedin FIG. 41, the gate electrode 12 is patterned on the first region A1 ofthe base 11.

After this, an insulating film (not illustrated) that is configured of,for example, a silicon nitride film is formed on the surface of the gateelectrode 12 and the second region A2 of the base 11. And then, theinsulating film is etched back. Thus, as illustrated in FIG. 42, theside wall SW is formed on the side surface 12B of the gate electrode 12.

After forming the side wall SW, as illustrated in FIG. 43, on the uppersurface 12A of the gate electrode 12, on a side surface of the side wallSW, and on the second region A2 of the base 11, the gate insulating film13 is formed by, for example, a CVD method. The gate insulating film 13may be configured of, for example, a layered film of a silicon nitridefilm and a silicon oxide film. The gate insulating film 13 may bepreferably formed with a uniform thickness.

After forming the gate insulating film 13, on the surface of the gateinsulating film 13, a semiconductor material film (not illustrated) thatis configured of the above-mentioned material, specifically polysilicon,is formed. The semiconductor material film is patterned to apredetermined shape by, for example, photolithography and etching. Thus,as illustrated in FIG. 44, the semiconductor layer 14 is formed on thesurface of the gate insulating film 13. The semiconductor layer 14 maybe preferably formed with a uniform thickness.

After forming the semiconductor layer 14, as illustrated in FIG. 45, onthe surface of the semiconductor layer 14, the insulating layer 15 isformed by, for example, a CVD method. The insulating film 15 may beconfigured of, for example, a layered film of a silicon oxide film and asilicon nitride film.

After forming the insulating film 15, as illustrated in FIG. 46, thecontact holes H1 are formed in the insulating film 15. Subsequently, asillustrated in FIG. 47, the source electrode 16S and the drain electrode16D are formed. The source electrode 16S and the drain electrode 16D areconnected to the semiconductor layer 14 through the contact holes H1.Thus, the thin film transistor 10C as illustrated in FIG. 38 iscompleted.

FIG. 48 illustrates an Id-Vd characteristic of the thin film transistor10C. It is to be noted that FIG. 48 also illustrates the result of thereference example 1 as well.

As seen from FIG. 48, in the thin film transistor 10C according to thepresent embodiment, an amount of kink occurring is reduced as comparedto the reference example 1. A possible reason may be as follows. Sincethe side wall SW is provided on the side surface 12B of the gateelectrode 12, the position P1 of the change in the distance D from thesemiconductor layer 14 to the gate electrode 12 is separated from theposition P2 where the semiconductor layer 14 bends in shape. This allowsa gradual change in the distance D, relaxing the concentration ofelectric field at the edge of the gate electrode 12. That is, it isknown that if the degree of inclination of the semiconductor layer 14with respect to the first region A1 at the side surface 12B of the gateelectrode 12 is different from the degree of inclination of the sidesurface 12B of the gate electrode 12 with respect to the first regionA1, it is possible to relax the local concentration of electric field inthe semiconductor layer 14.

As described above, in the present embodiment, the side wall SW isprovided on the side surface 12B of the gate electrode 12, allowing thedegree of inclination of the semiconductor layer 14 with respect to thefirst region A1 at the side surface 12B of the gate electrode 12 to bedifferent from the degree of inclination of the side surface 12B of thegate electrode 12 with respect to the first region A1. Hence, it ispossible to reduce the degree of bending of the shape of thesemiconductor layer 14 at the boundary position P1. This allows agradual change in the distance D from the semiconductor layer 14 to thegate electrode 12, making it possible to relax the local concentrationof electric field in the semiconductor layer 14.

Fifth Embodiment

FIG. 49 illustrates an overall configuration of a display deviceaccording to a fifth embodiment of the present disclosure. The displaydevice 100 includes, for example, a pixel array section 102 and a drivesection (a signal selector 103, a main scanner 104, and a power scanner105) that drives the pixel array section 102.

The pixel array section 102 includes a plurality of pixels PX arrangedin a matrix and power lines DSL101 to 10 m that are arranged incorrespondence with the respective rows of the plurality of pixels PX.Each of the pixels PX is disposed at an intersection at which scan linesWSL101 to 10 m in rows and signal lines DTL101 to 10 n in columnsintersect. Each of the pixels PX includes a pixel circuit 101.

The main scanner (a write scanner WSCN) 104 is adapted to supply, toeach of the scan lines WSL101 to 10 m, a control signal in turn,performing line sequential scanning of the pixels PX in units of row.The power scanner (DSCN) 105 is adapted to supply, to each of the powerlines DSL101 to 10 m, a power voltage that is switched between a firstpotential and a second potential, in accordance with the line sequentialscanning. The signal selector (a horizontal selector HSEL) 103 isadapted to supply, to the signal lines DTL101 to 10 n in columns, asignal potential as a picture signal and a reference potential inaccordance with the line sequential scanning.

FIG. 50 illustrates one example of a specific configuration andconnecting relation of the pixel circuit 101 illustrated in FIG. 49. Thepixel circuit 101 includes, for example, a light emitting element 3D,which is typified by an organic EL display element, and so on, asampling transistor 3A, a driving transistor 3B, and a storage capacitor3C.

The sampling transistor 3A includes a gate, a source, and a drain. Thegate is connected to the associated scan line WSL101. One of the sourceand the drain is connected to the associated signal line DTL101. Anotherof the source and the drain is connected to a gate g of the drivingtransistor 3B.

The driving transistor 3B includes the gate g, a source s, and a draind. One of the source s and the drain d is connected to the lightemitting element 3D. Another of the source s and the drain d isconnected to the associated power line DSL101. In the presentembodiment, the drain d of the driving transistor 3B is connected to thepower line DSL101, while the source s is connected to an anode of thelight emitting element 3D. A cathode of the light emitting element 3D isconnected to a ground wiring 3H. It is to be noted that the groundwiring 3H is wired commonly to all the pixels PX.

The storage capacitor 3C is connected between the source s and the gateg of the driving transistor 3B. The storage capacitor 3C is adapted toretain the signal potential of the picture signal that is supplied fromthe signal line DTL101.

FIG. 51 illustrates a cross-sectional configuration of one pixel PX ofthe display device 100. The display device 100 includes, for example,the thin film transistor 10 and a display element 20.

The thin film transistor 10 is, for example, a thin film transistor asdescribed above in the first embodiment. It is to be noted that, insteadof the thin film transistor 10, the thin film transistors 10A to 10Caccording to the second to fourth embodiments may be adoptable.

The display element 20 is configured of, for example, an organic ELelement and corresponds to the light emitting element 3D illustrated inFIG. 50. Specifically, the display element 20 is one of a red organic ELelement 20R that is adapted to produce red light, a green organic ELelement 20G that is adapted to produce green light, and a blue organicEL element 20B that is adapted to produce blue light (refer to FIG. 52).

The display element 20 is provided on a planarization layer 17illustrated in FIG. 51, and has a configuration in which an anodeelectrode (a first electrode) 21, a barrier rib 22, an organic layer 23,and a cathode electrode (a second electrode) 24 are stacked in thisorder. The display element 20 is an organic EL element of an uppersurface emission type (of a top emission type) in which holes injectedfrom the anode electrode 21 and electrons injected from the cathodeelectrode 24 are recombined in a light emission layer 23C (to bedescribed later) to produce light, and the light thus produced isextracted on an opposite side to the base 11 (on the cathode electrode24 side). The use of the organic EL element of the upper surfaceemission type allows an enhanced aperture ratio of a light emissionregion of the display device 100. It is to be noted that the displayelement 20 is not limited to the organic EL element of the upper surfaceemission type but may be an organic EL element of a lower surfaceemission type (of a bottom emission type), i.e. a transparent type inwhich light is extracted on the base 11 side, for example.

The planarization layer 17 is adapted to reduce unevenness due to thethin film transistor 10 for planarization. The planarization layer 17may have a thickness of, for example, about 2 μm, and may be configuredof an organic insulating film that includes acrylic, polyimide,siloxane, or the like as a material. The planarization layer 17 may alsobe configured of a layered film of a silicon oxide film, a siliconnitride film, or an aluminum oxide film, and an organic insulating filmsuch as acrylic, polyimide, siloxane, and so on.

In a case that the display device 100 is of an upper surface emissiontype, the anode electrode 21 may be configured of, for example, a highlyreflecting material, specifically, an alloy of aluminum and neodymium,aluminum (Al), titanium (Ti), chromium (Cr), and so on. In a case thatthe display device 100 is of a transparent type, the anode electrode 21may be configured of, for example, a transparent material, specifically,ITO, IZO (a registered trademark), IGZO, or the like. The anodeelectrode 21 is connected to the source electrode 16S through a contacthole H2.

The barrier rib 22 may be configured of, for example, an organicmaterial such as polyimide, novolac, or the like, and has a function ofsecuring insulation between the anode electrode 21 and the cathodeelectrode 24.

The organic layer 23 may have a configuration in which, as illustratedin FIG. 52 for example, a hole injection layer 23A, a hole transportlayer 23B, the light emission layer 23C (a red light emission layer23CR, a green light emission layer 23CG, and a blue light emission layer23CB), an electron transport layer 23D, and an electron injection layer23E are stacked in this order from the anode electrode 21 side. An uppersurface of the organic layer 23 is covered with the cathode electrode24. The red light emission layer 23CR is adapted to produce red lightLR. The green light emission layer 23CG is adapted to produce greenlight LG. The blue light emission layer 23CB is adapted to produce bluelight LB.

Alternatively, the organic layer 23 may have a configuration in which,as illustrated in FIG. 53 for example, the hole injection layer 23A, thehole transport layer 23B, the light emission layer 23C (a yellow lightemission layer 23CY and the blue light emission layer 23CB), theelectron transport layer 23D, and the electron injection layer 23E arestacked in this order from the anode electrode 21 side. In this case,the yellow light emission layer 23CY is adapted to produce yellow lightLY. The yellow light LY is adapted to be color-separated into the redlight LR and the green light LG by a color filter CF (a red filter CFRand a green filter CFG).

In another alternative, as illustrated in FIG. 54, for example, thelight emission layer 23C may be a white light emission layer having aconfiguration of a layered structure of the red light emission layer23CR, the blue light emission layer 23CB, and the green light emissionlayer 23CG. In this case, the light emission layer 23C is adapted toproduce white light LW. The white light LW is adapted to becolor-separated into the red light LR, the green light LG, and the bluelight LB by the color filter CF (the red filter CFR, the green filterCFG, and a blue filter CFB).

It is to be noted that the configurations of the organic layer 23 andthe light emission layer 23C are not limited to examples illustrated inFIGS. 52 to 54, and it goes without saying that they may have otherconfigurations.

In the organic layer 23, the hole injection layer 23A, the holetransport layer 23B, the electron transport layer 23D, and the electroninjection layer 23E may be formed as a common layer over an entiresurface of the pixel array section 102 (refer to FIG. 49) by, forexample, a vacuum deposition method. On the other hand, the red lightemission layer 23CR, the green light emission layer 23CG, and the yellowlight emission layer 23CY may be formed separately for each color by,for example, a coating method. The blue light emission layer 23CB may beformed as a common layer over the entire surface of the pixel arraysection 102 by, for example, a vacuum deposition method, or may beformed separately for each color by, for example, a coating method.

A thickness and a material of each layer that constitutes the organiclayer 23 may be exemplified as follows, though they are not limited inparticular.

The hole injection layer 23A is adapted to enhance an electron injectionefficiency into the light emission layer 23C. The hole injection layer23A is also adapted to be a buffer layer to prevent a leak. A thicknessof the hole injection layer 23A may be, for example, preferably 5 nm to200 nm both inclusive, and more preferably 8 nm to 150 nm bothinclusive. A constituent material of the hole injection layer 23A may beselected appropriately in relation to the materials of the electrodesand adjacent layers. Examples may include polyaniline, polythiophene,polypyrrole, polyphenylene vinylene, poly(thienylene vinylene),polyquinoline, polyquinoxaline, and their derivatives, a conductivepolymer such as a polymer that includes an aromatic amine structure in amain chain or in a side chain, metal phthalocyanine (such as copperphthalocyanine), carbon, and so on. Examples of conductive polymers mayinclude oligoaniline and polydioxythiophene such aspoly(3,4-ethylenedioxythiophehe) (PEDOT).

The hole transport layer 23B is adapted to enhance a hole transportefficiency into the light emission layer 23C. A thickness of the holetransport layer 23B may be, for example, preferably 5 nm to 200 nm bothinclusive, and more preferably 8 nm to 150 nm both inclusive, though itdepends on the whole configuration of the element. As a constituentmaterial of the hole transport layer 23B, a light emitting material thatis soluble to an organic solvent may be adopted. Examples may includepolyvinyl carbazole, polyfluorene, polyaniline, polysilane, or theirderivatives, a polysiloxane derivative that includes an aromatic aminein a side chain or in a main chain, polythiophene and its derivatives,polypyrrole, or Alq₃, and so on.

In the light emission layer 23C, when an electric field is applied,there occurs the recombination of holes and electrons, allowing light tobe produced. A thickness of the light emission layer 23C may be, forexample, preferably 10 nm to 200 nm both inclusive, and more preferably20 nm to 150 nm both inclusive, though it depends on the wholeconfiguration of the element. Each layer in the light emission layer 23Cmay be a single layer or may have a laminated structure.

As a constituent material of the light emission layer 23C, materialssuitable for the respective light emission colors may be adopted.Examples may include a polyfluorene-based polymer derivative, a(poly)paraphenylene vinylene derivative, a polyphenylene derivative, apolyvinyl carbazole derivative, a polythiophene derivative, apelylene-based pigment, a coumarin-based pigment, a rhodamine-basedpigment, or the above-mentioned polymer doped with an organic ELmaterial. Examples of materials to be doped may include rubrene,perylene, 9,10-diphenylanthracene, tetraphenyl butadiene, nile red,coumarin-6, and so on. It is to be noted that the constituent materialsof the light emission layer 23C may be a mixture of two or more of theabove-mentioned materials. The constituent materials of the lightemission layer 23C are not limited to the above-mentioned materials ofhigh molecular weight, but materials of low molecular weight may be usedin combination. Examples of materials of low molecular weight mayinclude benzene, styrylamine, triphenylamine, porphyrin, triphenylene,azatriphenylene, tetracyanoquinodimethane, triazole, imidazole,oxadiazole, polyaryl alkane, phenylenediamine, arylamine, oxazole,anthracene, fluorenone, hydrazone, stilbene, or their derivatives, or amonomer or an oligomer of a heterocyclic conjugated system such as apolysilane-based compound, a vinylcarbazole-based compound, athiophene-based compound, or an aniline-based compound.

As the constituent materials of the light emission layer 23C, inaddition to the above-mentioned materials, a material having high lightemission efficiency may be used as a light-emitting guest material.Examples may include an organic light emitting material such as afluorescent material of low molecule weight, a phosphorescent pigment,or a metal complex.

It is to be noted that the light emission layer 23C may be a lightemission layer having hole transporting property that also serves as theabove-mentioned hole transport layer 23B. Also, the light emission layer23C may be a light emission layer having electron transporting propertythat also serves as the electron transport layer 23D, which will bedescribed later.

The electron transport layer 23D and the electron injection layer 23Eare adapted to enhance an electron transport efficiency into the lightemission layer 23C. A total thickness of the electron transport layer23D and the electron injection layer 23E may be, for example, preferably5 nm to 200 nm both inclusive, and more preferably 10 nm to 180 nm bothinclusive, though it depends on the whole configuration of the element.

A constituent material of the electron transport layer 23D may bepreferably an organic material having excellent electron transportingperformance. Enhancing the transport efficiency of the light emissionlayer 23C allows variation in light emission colors due to intensity ofelectric field to be restrained. Specifically, for example, anarylpyridine derivative and a benzoimidazole derivative may bepreferably used. Thus, it is possible to maintain high electron supplyefficiency at a low drive voltage. Examples of constituent materials ofthe electron injection layer 23E may include an alkali metal, analkaline earth metal, a rare earth metal, and their oxides, compositeoxides, fluorides, carbonates, and so on.

The cathode electrode 24 may have a thickness of, for example, about 10nm, and may be configured of a material having good light transmittingproperty and a small work function. Alternatively, a transparentconductive film using an oxide may allow the light extraction to besecured. In this case, ZnO, ITO, IZnO, InSnZnO, and so on may be used.Furthermore, though the cathode electrode 24 may be a single layer, inexamples illustrated in FIGS. 52 to 54, the cathode electrode 24 has aconfiguration in which, for example, a first layer 24A, a second layer24B, and a third layer 24C are stacked in this order from the anodeelectrode 21 side.

The first layer 24A may be preferably configured of a material having asmall work function and good light transmitting property. Specificexamples may include an alkaline earth metal such as calcium (Ca),barium (Ba), or the like, an alkali metal such as lithium (Li), caesium(Cs), or the like, indium (In), magnesium (Mg), and silver (Ag).Furthermore, other examples may include an alkali metal oxide, an alkalimetal fluoride, an alkaline earth metal oxide, an alkaline earth metalfluoride, specifically, Li₂O, Cs₂CO₃, Cs₂SO₄, MgF, LiF, CaF₂, or thelike.

The second layer 24B may be configured of a material having lighttransmitting property and good electrical conductivity, such as a thinfilm Mg—Ag electrode or a Ca electrode. The third layer 24C may bepreferably configured of a transparent lanthanoid-based oxide torestrain degradation of the electrode. This makes it possible to use thethird layer 24C as a sealing electrode that allows light to be extractedthrough the upper surface. In the case of the bottom emission type, gold(Au), platinum (Pt), or Au—Ge, or the like may be used for a material ofthe third layer 24C.

It is to be noted that the first layer 24A, the second layer 24B, andthe third layer 24C may be formed by techniques such as a vacuumdeposition method, a sputtering method, a plasma CVD (chemical vapordeposition) method, and the like. In a case that a driving method of thedisplay device 100 is an active matrix method, the cathode electrode 24may be formed as a continuous film on the base 11, constituting a commonelectrode to the display elements 20, in a state that the cathodeelectrode 24 is insulated from the anode electrode 21 by the barrier rib22 and the organic layer 23.

The cathode electrode 24 may be a mixed layer that includes an organiclight emitting material such as an aluminum quinoline complex, astyrylamine derivative, a phthalocyanine derivative. In this case, thecathode electrode 24 may further include an additional layer havinglight transmitting property such as Mg—Ag, as the third layer 24C (notillustrated). The cathode electrode 24 is not limited to theabove-mentioned stacked structure, but it goes without saying that anoptimum combination or stacked structure may be adopted according to theconfiguration of the device to be manufactured. For example, theconfiguration of the cathode electrode 24 according to theabove-described present embodiment is a stacked structure of layershaving respectively separated functions, in which an inorganic layer(the first layer 24A) that facilitates electron injection into theorganic layer 23, an inorganic layer (the second layer 24B) thatcontrols the electrode, and an inorganic layer (the third layer 24C)that protects the electrode are separated. However, the inorganic layerthat facilitates electron injection into the organic layer 23 may alsoserve as the inorganic layer that controls the electrode. Alternatively,these layers may constitute a single layer.

Furthermore, in a case that the display element 20 has a cavitystructure, the cathode electrode 24 may be preferably configured of asemitransparent and semireflecting material. This makes it possible toallow multiple interference of produced light between a light reflectingplane on the anode electrode 21 side and a light reflecting plane on thecathode electrode 24 side, allowing the light to be extracted on thecathode electrode 24 side. In this case, an optical distance between thelight reflecting plane on the anode electrode 21 side and the lightreflecting plane on the cathode electrode 24 side may be determined by awavelength of the light to be extracted. The thickness of each layer maybe assumed to be set to satisfy the optical distance. In such a displayelement of the upper surface light emission type, the positive use ofthe cavity structure allows improvement in the light extractionefficiency to the outside and the control of the light emissionspectrum.

Above the display element 20, there may be provided, for example, aprotective layer 25, an adhesive layer 26, and a sealing substrate 27,which are adapted to seal the display element 20 (a solid sealingstructure).

The protective layer 25 is adapted to prevent water from intruding intothe organic layer 23. The protective layer 25 may be configured of amaterial having low permeability and low water permeability and may havea thickness of, for example, 2 μm to 3 μm both inclusive. A material ofthe protective layer 25 may be either an insulating material or aconductive material. Examples of insulating materials may includeinorganic amorphous insulating material such as amorphous silicon(α-Si), amorphous silicon carbide (α-SiC), amorphous silicon nitride(α-Si_(1-x)N_(x)), amorphous carbon (α-C), and so on. Such inorganicamorphous insulating materials have low water permeability since they donot constitute grains, making a good protective film.

The sealing substrate 27 is disposed on the cathode electrode 24 side ofthe display element 20, and is adapted to seal the display element 20together with the adhesive layer 26. The sealing substrate 27 may beconfigured of a transparent material with respect to the light producedin the display element 20, specifically, glass, or the like. The sealingsubstrate 27 may be provided with, for example, a color filter and alight shielding film as a black matrix (both not illustrated), allowingthe light produced in the display element 20 to be extracted andabsorbing the external light that is reflected by wirings between thedisplay elements 20 to improve contrast.

The color filter may include the red filter, the green filter, and theblue filter (neither illustrated), which are arranged in order. The redfilter, the green filter, and the blue filter are formed in, forexample, a square shape with little space between them. The red filter,the green filter, and the blue filter each may be configured of a resinmixed with a pigment. Selection of a pigment allows adjustment of lighttransmitting property so that light transmittance in a target wavelengthregion, i.e. red, green, or blue, is high while light transmittance inother wavelength regions are low.

The light shielding film may be configured of a black resin film that ismixed with, for example, a black colorant and has an optical density of1 or more, or a thin film filter that utilizes interference in thinfilms. Among them, the configuration with the black resin film may bepreferable, allowing low-cost and easy fabrication. The thin film filtermay have, for example, a lamination of one or more layers of thin filmsthat are configured of a metal, a metal nitride, or a metal oxide,allowing light to be attenuated utilizing interference in thin films.Specific examples of the thin film filters may include an alternatelamination of chromium (Cr) and chromium (III) oxide (Cr₂O₃).

In the display device 100, the sampling transistor 3A becomes conductivein response to the control signal supplied from the scan line WSL, andthe signal potential of the picture signal is sampled. The sampledsignal potential is retained by the storage capacitor 3C. In themeanwhile, the driving transistor 3B is supplied with a current from thepower line DSL, allowing a drive current to be supplied to the lightemitting element 3D (the display element 20) according to the signalpotential retained by the storage capacitor 3C. The light emittingelement 3D (the display element 20) emits light by the drive currentthus supplied, at luminance according to the signal potential of thepicture signal. The light is extracted through the cathode electrode 24,the color filter, and the sealing substrate 27.

Here, since the local concentration of electric field in thesemiconductor layer 14 of the thin film transistor 10 is relaxed, theoccurrence of a kink current or degradation in reliability of the thinfilm transistor 10 is restrained. Thus, defects of pixel characteristicsare reduced, and display quality is improved.

Modification Example 3

FIG. 55 illustrates a plan configuration of a display device 100Baccording to a modification example 3 of the present disclosure. Thepresent modification example involves a display element 80 that isconfigured of a liquid crystal display element. Otherwise, the displaydevice 100B has similar configurations, functions and effects to thoseof the display device 100 according to the above-described embodiment,and may be manufactured similarly to the above-described embodiment.Therefore, description will be given with similar components denoted bysame reference numerals.

The display element 80 has a configuration in which, for example, aliquid crystal layer 83 is sealed between a pixel electrode 81 and anopposite electrode 82. The faces on the liquid crystal layer 83 side ofthe pixel electrode 81 and the opposite electrode 82 are provided withorientation films 84A and 84B. The pixel electrode 81 is provided foreach pixel and is connected to the source electrode 16S through thecontact hole H2 provided in the planarization layer 17. The oppositeelectrode 82 is provided, on an opposite substrate 86, as a commonelectrode to a plurality of pixels and is configured to be maintainedat, for example, a common potential. The liquid crystal layer 83 may beconfigured of a liquid crystal that is to be driven by, for example, avertical alignment (VA) mode, a twisted nematic (TN) mode, or an inplane switching (IPS) mode, or the like.

Moreover, below the base 11, there is provided a backlight 87. On thebacklight 87 side of the base 11 and on the opposite substrate 86,polarization plates 88A and 88B are attached.

Modification Example 4

FIG. 56 illustrates a plan configuration of an electrophoretic element91 that constitutes a display element of a display device according to amodification example 4 of the present disclosure. FIG. 57 illustrates across-sectional configuration of the electrophoretic element 91. Theelectrophoretic element 91 is adapted to produce contrast utilizing anelectrophoretic phenomenon and may be applied to various electronicapparatuses such as display devices. The electrophoretic element 91includes, in an insulating liquid 92, a phoretic particle 93 (a firstparticle) and a porous layer 94 having a pore 94A. It is to be notedthat FIGS. 56 and 57 schematically illustrates a configuration of theelectrophoretic element 91 and the illustration may be different fromactual dimentions or shapes.

The insulating liquid 92 may be configured of, for example, an organicsolvent such as paraffin or isoparaffin. For the insulating liquid 92,either one kind of organic solvent or a plurality of kinds of organicsolvents may be used. A viscosity and a refractive index of theinsulating liquid 92 may be preferably as low as possible. Lowering theviscosity of the insulating liquid 92 allows mobility (response speed)of the phoretic particle 93 to be enhanced. In accordance with this,energy (power consumption) for movement of the phoretic particle 93 isreduced. Lowering the refractive index of the insulating liquid 92allows an increase in a difference in refractive index between theinsulating liquid 92 and the porous layer 94, leading to higherreflectivity of the porous layer 94.

To the insulating liquid 92, for example, a colorant, a charge adjustingagent, a dispersion stabilizer, a viscosity adjusting agent, asurfactant, or a resin may be added.

The phoretic particle 93 dispersed in the insulating liquid 92 may beone charged particle, or two or more charged particles. Such a chargedphoteric particle 93 is adapted to move through the pore 94A in responseto electric field. The phoretic particle 93 has an arbitrary opticalreflective characteristic (light reflectivity). A difference between thelight reflectivity of the phoretic particle 93 and the lightreflectivity of the porous layer 94 allows contrast to be produced. Forexample, the phoretic particle 93 may perform bright display while theporous layer 94 may perform dark display. Alternatively, the phoreticparticle 93 may perform dark display while the porous layer 94 mayperform bright display.

When viewing the electrophoretic element 91 from the outside, in thecase that the phoretic particle 93 performs bright display, the phoreticparticle 93 is visually recognized in, for example, white color or nearwhite color. In the case that the phoretic particle 93 performs darkdisplay, the phoretic particle 93 is visually recognized in, forexample, black color or near black color. The color of the phoreticparticle 93 is not limited as long as it is possible to producecontrast.

The phoretic particle 93 may be configured of, for example, an organicpigment, an inorganic pigment, a dye, a carbon material, a metalmaterial, a metal oxide, particles (powder) of glass or a polymermaterial (a resin), and so on. For the phoretic particle 93, either onekind of these, or two or more kinds of these may be used. It may bepossible to configure the phoretic particle 93 of a crushed particle, acapsule particle, and so on of a resin solid content that includes theabove-mentioned particle. It is to be noted that materials thatcorrespond to the above-mentioned carbon material, the metal material,the metal oxide, the glass, or the polymer material are excluded fromthe materials that correspond to the organic pigment, the inorganicpigment, or the dye. A particle diameter of the phoretic particle 93 maybe, for example, 30 nm to 300 nm both inclusive.

Examples of the above-mentioned organic pigments may include anazo-based pigment, a metal-complex-azo-based pigment, poly condensedazo-based pigment, a flavanthrone-based pigment, a benzimidazolone-basedpigment, a phthalocyanine-based pigment, a quinacridone-based pigment,an anthraquinone-based pigment, a pelylene-based pigment, apelynone-based pigment, an anthrapyridine-based pigment, apyranthrone-based pigment, a dioxazine-based pigment, a thioindigo-basedpigment, an isoindolinone-based pigment, a quinophthalone-based pigment,an indanthrene-based pigment, or the like. Examples of the inorganicpigments may include zinc oxide, antimony white, iron black, titaniumboride, red iron oxide, mapico yellow, red lead, cadmium yellow, zincsulfide, lithophone, barium sulfide, cadmium celenide, calciumcarbonate, barium sulphate, lead chromate, lead sulfate, bariumcarbonate, lead white, alumina white, or the like. Examples of the dyesmay include a nigrosine-based dye, an azo-based dye, aphthalocyanine-based dye, a quinophthalone-based dye, ananthraquinone-based dye, a methine-based dye, or the like. Examples ofthe carbon materials may include carbon black, or the like. Examples ofthe metal materials may include gold, silver, copper, or the like.Examples of the metal oxides may include titanium oxide, zinc oxide,zirconium oxide, barium titanate, a copper-chromium oxide, acopper-manganese oxide, a copper-iron-manganese oxide, acopper-chromium-manganese oxide, or a copper-iron-chromium oxide, or thelike. Examples of polymer materials may include a polymer compound intowhich a functional group having a light absorbing region in a visiblelight region is introduced, or the like. Such a polymer compound is notlimited in particular in terms of kind, as long as the polymer compoundhas the light absorbing region in the visible light region.

Selection of a specific material of the phoretic particle 93 may bemade, for example, according to a role the phoretic particle 93 plays inproducing contrast. In the case that the phoretic particle 93 performsbright display, for example, the metal oxide such as titanium oxide,zinc oxide, zirconium oxide, barium titanate, or potassium titanate, orthe like may be used for the phoretic particle 93. In the case that thephoretic particle 93 performs dark display, for example, the carbonmaterial such as carbon black, the metal oxide such as a copper-chromiumoxide, a copper-manganese oxide, a copper-iron-manganese oxide, acopper-chromium-manganese oxide, and a copper-iron-chromium oxide, orthe like may be used for the phoretic particle 93. Among them, thecarbon material may be preferably used for the phoretic particle 93. Thephoretic particle 93 made of the carbon material exhibits excellentchemical stability, mobility, and light absorbing property.

An amount (a concentration) of the phoretic particle 93 contained in theinsulating liquid 92 may be, though not being limited in particular, 0.1percent by weight to 10 percent by weight both inclusive, for example.In this concentration range, shielding property and mobility of thephoretic particle 93 are secured. Specifically, when the amount of thephoretic particle 93 contained is smaller than 0.1 percent by weight,the phoretic particle 93 hardly shield (conceal) the porous layer 94,causing a possibility of difficulty in generating sufficient contrast.On the other hand, when the amount of the phoretic particle 93 containedis larger than 10 percent by weight, dispersion property of the phoreticparticle 93 is lowered. Therefore, there is a possibility of difficultyin phoresis of the phoretic particle 93, causing condensation.

It is preferable that the phoretic particle 93 be easily dispersed andcharged in the insulating liquid 92 for a long period. Also, it ispreferable that the phoretic particle 93 be hardly absorbed on theporous layer 94. Therefore, for example, a dispersion agent may be addedto the insulating liquid 92. The dispersion agent may be used togetherwith the charge adjusting agent.

The dispersion agent or the charge adjusting agent includes, forexample, either one or both of positive and negative charges, and isadapted to increase an amount of charges in the insulating liquid 92 andto allow the phoretic particles 93 to disperse due to electrostaticrepulsion. Examples of the dispersion agents may include “Solsperce”series manufactured by the Lubrizol Corporation, “BYK” series or“Anti-Terra” series manufactured by BYK-Chemie, or “Span” seriesmanufactured by TCI America, Inc.

In order to enhance the dispersing property of the phoretic particles93, surface treatment may be applied to the phoretic particles 93.Examples of the surface treatment may include rosin treatment,surfactant treatment, pigment derivative treatment, coupling agenttreatment, graft polymerization treatment, or microcapsulationtreatment, or the like. In particular, by performing graftpolymerization treatment, microcapsulation treatment, or a combinationthereof, it is possible to maintain dispersion stability of the phoreticparticle 93 for a long period.

For the surface treatment, for example, a material (an absorptivematerial) that includes a functional group capable of being absorbed ona surface of the phoretic particle 93 and a polymerizable functionalgroup, and so on may be used. A functional group capable of beingabsorbed may be determined according to a material that forms thephoretic particle 93. For example, in a case that the phoretic particle93 is configured of a carbon material such as carbon black, an anilinederivative such as 4-vinylaniline may be absorbed. In a case that thephoretic particle 93 is configured of a metal oxide, an organosilanederivative such as 3-(trimethoxy silyl) propyl methacrylate may beabsorbed. Examples of polymerizable functional groups may include avinyl group, an acrylic group, a methacrylic group, and so on.

It may be possible to introduce a polymerizable functional group intothe surface of the phoretic particle 93 and to perform the surfacetreatment by allowing the polymerizable functional group to be grafted(a grafted material). The grafted material may include, for example, apolymerizable functional group and a functional group for dispersion.The functional group for dispersion is adapted to allow the phoreticparticle 93 to be dispersed in the insulating liquid 92 and to maintainthe dispersing property by steric hindrance. In a case that theinsulating liquid 92 is, for example, paraffin, a branched alkyl groupand so on may be used for the functional group for dispersion. Examplesof polymerizable functional groups may include a vinyl group, an acrylicgroup, a methacrylic group, and so on. In order to allow the graftedmaterial to be polymerized and grafted, for example, a polymerizationinitiator such as azobisisobutyronitrile (AIBN) may be used.

Details of a method of dispersing the above-mentioned phoretic particle93 in the insulating liquid 92 is included in books such as “Dispersiontechnology of ultrafine particles and its evaluation—surfacetreatment⋅pulverization and dispersion stabilization inatmosphere/liquid/polymer” published by Science & Technology Co. Ltd.

The porous layer 94 is adapted to be capable of shielding the phoreticparticle 93, and may include a fibrous structure 94B and non-phoreticparticle 94C (a second particle) that is supported by the fibrousstructure 94B. The porous layer 94 may be a three-dimensional structure(an irregular network structure such as nonwoven fabric) formed by thefibrous structure 94B, and may be provided with a plurality of gaps (thepores 94A). The fibrous structure 94B constitutes the three-dimensionalstructure of the porous layer 94, allowing light (external light) to beirregularly reflected (multiply-scattered) and increasing reflectivityof the porous layer 94. Therefore, it is possible to obtain highreflectivity even in a case that a thickness of the porous layer 94 issmall. This makes it possible to improve contrast of the electrophoreticelement 91 and to reduce the energy for the movement of the phoreticparticle 93. Moreover, an average pore diameter of the pore 94A becomeslarger, and the number of the pores 94A provided in the porous layer 94is increased. Thus, the movement of the phoretic particle 93 through thepore 94A is facilitated, increasing response speed and further reducingthe energy for the movement of the phoretic particle 93. The thicknessof the porous layer 94 may be, for example, 5 μm to 100 μm bothinclusive.

The fibrous structure 94B may be a fibrous substance having a sufficientlength with respect to a fiber diameter (diameter). For example, aplurality of fibrous structures 94B may be collected and randomlyoverlapped to constitute the porous layer 94. One fibrous structure 94Bmay be randomly entangled to constitute the porous layer 94.Alternatively, the porous layer 94 formed of one fibrous structure 94Band the porous layer 94 formed of the plurality of fibrous structures94B may be mixedly present.

The fibrous structure 94B may be configured of, for example, a polymermaterial or an inorganic material, or the like. Examples of polymermaterials may include nylon, polylactic acid, polyamide, polyimide,polyethylene terephthalate, polyacrylonitrile, polyethylene oxide,polyvinyl carbazole, polyvinyl chloride, polyurethane, polystyrene,polyvinyl alcohol, polysulfone, polyvinylpyrrolidone, polyvinylidenefluoride, polyhexafluoropropylene, cellulose acetate, collagen, gelatin,chitosan, or a copolymer thereof, and so on. Examples of the inorganicmaterials may include titanium oxide, and so on. For fibrous structure94B, the polymer material may be preferably used. This is because thepolymer materials have low reactivity with, for example, light, and arechemically stable. In other words, the use of the polymer materialsmakes it possible to prevent an unintended decomposition reaction of thefibrous structure 94B. In a case that the fibrous structure 94B isconfigured of a material having high reactivity, it is preferable that asurface be covered with an arbitrary protective film.

The fibrous structure 94B may extend, for example, linearly. The fibrousstructure 94B may have whatever shape. For example, the fibrousstructure 94B may shrink, or bends halfway. Alternatively, the fibrousstructure 94B may be branched halfway.

An average fiber diameter of the fibrous structure 94B may be, forexample, 50 nm to 2000 nm both inclusive. However, the average fiberdiameter may fall out of the above-mentioned range. By reducing theaverage fiber diameter, it is possible to allow light to be easilyirregularly reflected and to increase the pore diameter of the pore 94A.The fiber diameter may be determined so that the fibrous structure 94Bis capable of support the non-phoretic particle 94C. The average fiberdiameter may be measured by, for example, microscope observation using ascanning type electron microscope. An average length of the fibrousstructure 94B may be arbitrary. The fibrous structure 94B may be formedby, for example, a phase separation method, a phase inversion method, anelectrostatic spinning (electrospinning) method, a melt spinning method,a wet spinning method, a dry spinning method, a gel spinning method, asol-gel method, or a spray coating method, or the like. The use of suchmethods makes it possible to form easily and steadily the fibrousstructure 94B that has a sufficient length with respect to the fiberdiameter.

The fibrous structure 94B may be preferably configured of nanofiber.Here, nanofiber refers to fibrous substance having a fiber diameter of 1nm to 1000 nm both inclusive and having a length 100 times larger thanthe fiber diameter. The use of the nanofiber as the fibrous structure94B facilitates irregular reflection of light, contributing to furtherenhancement of reflectivity of the porous layer 94. That is, it ispossible to improve contrast of the electrophoretic element 91.Moreover, in the fibrous structure 94B made of nanofiber, a ratio ofvolume occupied by the pore 94A in unit volume becomes larger,facilitating the movement of the phoretic particle 93 through the pore94A. Therefore, it is possible to reduce the energy for the movement ofthe phoretic particle 93. The fibrous structure 94B made of nanofibermay be preferably formed by the electrostatic spinning method. The useof the electrostatic spinning method makes it possible to form easilyand steadily the fibrous structure 94B of a small fiber diameter.

For the fibrous structure 94B, one that has different light reflectivityfrom that of the phoretic particle 93 may be preferably used. Thus, itis possible to easily generate contrast due to a difference in lightreflectivity between the porous layer 94 and the phoretic particle 93.The fibrous structure 94B that exhibits light transparency (that iscolorless and transparent) in the insulating liquid 92 may also be used.

The pore 94A is configured by overlap of the plurality of the fibrousstructures 94B or by entanglement of one fibrous structure 94B. The pore94A may preferably have an average pore diameter as large as possible inorder to facilitate the movement of the phoretic particle 93 through thepore 94A. The average pore diameter of the pore 94A may be, for example,0.1 μm to 10 μm both inclusive.

The non-phoretic particle 94C is fixed to the fibrous structure 94B, andhas different light reflectivity from that of the phoretic particle 93.The non-phoretic particle 94C may be configured of a same material asthat of the above-mentioned phoretic particle 93. Specifically, in acase that the non-phoretic particle 94C (the porous layer 94) performsbright display, a same material as that of the phoretic particle 93 in acase that the phoretic particle 93 performs bright display may be used.In a case that the non-phoretic particle 94C (the porous layer 94)performs dark display, a same material as that of the phoretic particle93 in a case that the phoretic particle 93 performs dark display. In acase that the porous layer 94 performs bright display, the non-phoreticparticle 94C may be preferably configured of a metal oxide. Thus, it ispossible to obtain excellent chemical stability, fixation and lightreflectivity. In particular, the non-phoretic particle 94C may bepreferably configured of a metal oxide having a high refractive index,for example, titanium oxide of rutile type. The constituent material ofthe non-phoretic particle 94C may be same as or different from that ofthe phoretic particle 93. The non-phoretic particle 94C may be fullyburied inside of the fibrous structure 94B, or alternatively, may bepartially exposed from the fibrous structure 94B. A color that isvisually recognized externally when the non-phoretic particle 94Cperforms bright display or dark display is similar to that as describedabove with respect to the phoretic particle 93.

The porous layer 94 may be manufactured as follows, for example. First,a constituent material of the fibrous structure 94B such as a polymermaterial or the like is dissolved in, for example, an organic solvent orthe like, preparing a spinning solution. Next, the non-phoretic particle94C is added to the spinning solution, and the solution is sufficientlystirred to allow the non-phoretic particle 94C to be dispersed. Finally,spinning is carried out by, for example, an electrostatic spinningmethod from the spinning solution. Thus, the non-phoretic particle 94Cis fixed to the fibrous structure 94B to form the porous layer 94. Inorder to form the pore 94A in the porous layer 94, a polymer film may besubjected to a piercing process using laser. Alternatively, for theporous layer 94, a cloth knitted of a synthetic fiber or the like, or anopen-cell porous polymer, or the like may also be used.

The electrophoretic element 91 is adapted, as described above, togenerate contrast due to the difference between the light reflectivityof the phoretic particle 93 and the light reflectivity of the porouslayer 94. Specifically, out of the phoretic particle 93 and the porouslayer 94, the light reflectivity of what performs bright display ishigher than the light reflectivity of what performs dark display.Preferably, the light reflectivity of the non-phoretic particle 94C ishigher than that of the phoretic particle 93, allowing the porous layer94 to perform bright display and allowing the phoretic particle 93 toperform dark display. By performing such display, the light reflectivityin performing bright display is allowed to be remarkably increasedutilizing the irregular reflection of light by the porous layer 94 (thethree-dimensional structure). Therefore, in accordance with this, thecontrast is remarkably enhanced.

In the electrophoretic element 91, within a range where an electricfield is applied, the phoretic particle 93 moves through the pore 94A ofthe porous layer 94. In correspondence with a region where the phoreticparticle 93 have moved and a region where the phoretic particle 93 havenot moved, either bright display or dark display is performed, allowingan image to be displayed.

FIG. 58 illustrates a cross-sectional configuration of a display device100C using the electrophoretic element 91 as the display element. Thedisplay device 100C is an electrophoretic display device (a so-calledelectronic paper display device) that is adapted to display an image(for example, character information and so on) utilizing theelectrophoretic phenomenon. The display device 100C may include, forexample, on the base 11, a display element 90 that is configured of theelectrophoretic element 91.

The display element 90 includes a pixel electrode 95, theabove-described electrophoretic element 91, and an opposite substrate96. A spacer (not illustrated) is interposed between the planarizationlayer 17 on the base 11 and the opposite substrate 96.

The pixel electrode 95 may be formed of, for example, a metal materialsuch as gold (Au), silver (Ag), or copper (Cu), or the like. The pixelelectrode 95 is connected to the source electrode 16S through thecontact hole H2. The pixel electrode 95 may be arranged, for example, ina matrix or in a segment shape according to a pixel layout.

The opposite substrate 96 includes, for example, a plate member 96A andan opposite electrode 96B. The opposite electrode 96B may be formed onan entire surface (a surface facing the base 11) of the plate member96A. The opposite electrode 96B may be arranged, similarly to the pixelelectrode 95, in a matrix or in a segment shape.

The plate member 96A has light transparency and may be configured of,for example, an inorganic material, a metal material, or a plasticmaterial, or the like. Examples of inorganic materials may includesilicon (Si), silicon oxide (SiOx), silicon nitride (SiNx), or aluminumoxide (AlOx), and so on. Examples of silicon oxide may include glass, orspin on glass (SOG), or the like. Examples of metal materials mayinclude aluminum (Al), nickel (Ni), or stainless steel, or the like.Examples of plastic materials may include polycarbonate (PC),polyethylene terephthalate (PET), polyethylene naphthalate (PEN), orpolyethyl ether ketone (PEEK), or the like.

For the opposite electrode 96B, the following light transparentconductive materials (transparent electrode materials) may be used. Forexample, indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO),fluorine doped tin oxide (FTO), or aluminum doped zinc oxide (AZO).

In a case that an image is displayed on the opposite substrate 96 side,the electrophoretic element 91 is viewed through the opposite electrode96B. Therefore, the light transparency (light transmittance) of theopposite electrode 96B is preferably as high as possible, for example,80 percent or more. Moreover, electrical resistance of the oppositeelectrode 96B is preferably as low as possible, for example, 100Ω/□ orless.

The electrophoretic element 91 includes, as described above, in theinsulating liquid 92, the phoretic particle 93, the porous layer 94including the plurality of pores 94A. The insulating liquid 92 is filledin a space between the planarization layer 17 and the opposite substrate96. The porous layer 94 is supported by, for example, the spacer (notillustrated). The space where the insulating liquid 92 is filled isdivided into, for example, a retreat region R1 and a display region R2with the porous layer 94 as a boundary. The retreat region R1 is on theside closer to the pixel electrode 95. The display region R2 is on theside closer to the opposite electrode 96B. Configurations of theinsulating liquid 92, the phoretic particle 93, and the porous layer 94may be same as described above. It is to be noted that, in FIG. 58 andFIG. 59, which is to be described later, part of the pores 94A are shownfor simplicity of the figures.

The porous layer 94 may be adjacent to either one of the pixel electrode95 and the opposite electrode 96B. The retreat region R1 and the displayregion R2 may not be divided clearly. The phoretic particle 93 isadapted to move toward the pixel electrode 95 or the opposite electrode96B in response to an electric field.

A thickness of the spacer (not illustrated) may be, for example, 10 μmto 100 μm both inclusive. The thickness of the spacer (not illustrated)is preferably as thin as possible. Thus, it is possible to reduce powerconsumption. The spacer (not illustrated) may be configured of, forexample, an insulating material such as a polymer material, or the like,and is provided in a lattice shape between the planarization layer 17and the opposite substrate 96. An arrangement and a shape of the spacer(not illustrated) are not limited in particular, but may be preferablyprovided so that the movement of the phoretic particle 93 is nothindered and the phoretic particles 93 are distributed uniformly.

In the display device 100C in an initial state, the phoretic particle 93is disposed in the retreat region R1 (FIG. 58). In this case, thephoretic particle 93 is shielded by the porous layer 94 in all thepixels. Therefore, when viewed from the opposite substrate 96 side, theelectrophoretic element 91 is in a no-contrast-generated (no-display)state.

On the other hand, when a pixel is selected by the thin film transistor10 on the base 11, and an electric filed is applied between the pixelelectrode 95 and the opposite electrode 96B, as illustrated in FIG. 59,the phoretic particle 93 moves, for each pixel, from the retreat regionR1 to the display region R2 through the porous layer 94 (the pores 94A).In this case, there are a pixel where the phoretic particle 93 isshielded by the porous layer 94 and a pixel where the phoretic particle93 is not shielded by the porous layer 94. Therefore, when viewed fromthe opposite substrate 96 side, the electrophoretic element 91 is in acontrast-generated state. Thus, an image is displayed.

APPLICATION EXAMPLES

In the following, description will be given on application examples ofthe display device according to the above-described example embodimentwith reference to FIGS. 60 to 74. The display device according toabove-described example embodiment may be applied to an electronicapparatus in various fields, for example, a television set, a digitalcamera, a notebook personal computer, a mobile terminal device such as amobile phone and a smart phone or a video camera. In other words, thedisplay device may be applied to an electronic apparatus in variousfields that is configured to display an image or a picture based on apicture signal input from outside or generated inside.

Module

The display device according to above-described example embodiment maybe incorporated, in a form of a module as illustrated in FIG. 60, in anelectronic apparatus such as application examples 1 to 9, which will beexemplified in the followings. The module includes, for example, a pixelregion 3 in the center of the base 11 and a peripheral region 4 outsidethe pixel region 3. In the pixel region 3, provided is a pixel arraysection 102 as illustrated in FIG. 49. In the peripheral region 4,provided is a drive section (the signal selector 103, the main scanner104, and the power scanner 105) as illustrated in FIG. 49. Also in theperipheral region 4, provided are external connection terminals (notillustrated) that are extended from wirings of the pixel array section102. To the external connection terminals, a flexible printed circuit(FPC) 9 for signal input and output may be connected.

Application Example 1

FIGS. 61 and 62 illustrate an appearance configuration of an electronicbook 210. The electronic book 210 includes, for example, a displaysection 211 and a non-display section 212, and an operation section 213.It is to be noted that the operation section 213 may be provided eitheron a front face of the non-display section 212 as illustrated in FIG.61, or on an upper face of the non-display section 212 as illustrated inFIG. 62. The display section 211 is configured of the display deviceaccording to the above-described example embodiment. It is to be notedthat the display device according to the above-described exampleembodiment may be mounted on a personal digital assistant (PDA) having asimilar configuration to that of the electronic book as illustrated inFIGS. 61 and 62.

Application Example 2

FIGS. 63 and 64 illustrate an appearance of a smart phone 220. The smartphone 220 includes, for example, a display section 221 and an operationsection 222 on a front side, and a camera 223 on a back side. Thedisplay section 221 is configured of the display device according to theabove-described example embodiment.

Application Example 3

FIG. 65 illustrates an appearance of a television set 230 to which thedisplay device according to the above-described example embodiment isapplied. The television set 230 includes, for example, a picture displayscreen section 233 that includes a front panel 231 and a filter glass232. The picture display screen section 233 is configured of the displaydevice according to the above-described example embodiment.

Application Example 4

FIG. 66 illustrates an appearance of a tablet personal computer 240. Thetablet personal computer 240 includes, for example, a touch panelsection 241 and a casing 242. The touch panel section 241 is configuredof the display device according to the above-described exampleembodiment.

Application Example 5

FIGS. 67 and 68 illustrate an appearance of a digital still camera 250.The digital still camera 250 includes, for example, a lighting sectionfor flash lighting 251, a display section 252, a menu switch 253, and ashutter button 254. The display section 252 is configured of the displaydevice according to the above-described example embodiment.

Application Example 6

FIG. 69 illustrates an appearance of a notebook personal computer 260.The notebook personal computer 260 includes, for example, a main body261, a keyboard 262 for input operations of characters and the like, anda display section 263 for image display. The display section 263 isconfigured of the display device according to the above-describedexample embodiment.

Application Example 7

FIG. 70 illustrates an appearance of a video camera 270. The videocamera 270 includes, for example, a main body 271, a lens 272 forphotographing an object, which is provided on a front side face of themain body 271, a start/stop switch 273 in photographing, and a displaysection 274. The display section 274 is configured of the display deviceaccording to the above-described example embodiment.

Application Example 8

FIGS. 71 and 72 illustrates an appearance of another electronic book280. The electronic book 280 is a thin flexible display formed of acomponent of a soft material. In the electronic book 280, the wholedevice is configured to be closed (folded) or opened as if an actualbook manufactured by binding a plurality of sheets of paper. This allowsa user to view contents displayed on the electronic book 280 (forexample, pages of a book, and so on), giving the user a sensation ofactual book reading.

The electronic book 280 includes, on a support substrate 281, a displaysection 282. The electronic book 280 also includes a hinge section 283at a back portion (a back 283A) of a book. On a lower surface side (asurface on the outside when closed) of the electronic book 280, providedis a cover 284 made of a soft resin film. An upper surface side (asurface on the inside when closed) is covered with a protective sheet285 made of a resin film that is soft and transparent to display light.The display section 282 is configured of the display device according tothe above-described example embodiment.

Application Example 9

FIGS. 73 and 74 illustrate an appearance of a mobile phone 290. Themobile phone 290 has a configuration, for example, in which an uppercasing 291 and a lower casing 292 are linked by a connection section (ahinge section) 293, and includes a display 294, a sub-display 295, apicture light 296, and a camera 297. The display 294 or the sub-display295 is configured of the display device according to the above-describedexample embodiment.

Although description has been made by giving the example embodiment asmentioned above, the contents of the present technology are not limitedto the above-mentioned example embodiment and may be modified in avariety of ways.

For example, in the above-described example embodiment, description hasbeen given on specific configurations of the display devices 100, and100A to 100C. However, the display devices 100, and 100A to 100C are notlimited to display devices including all the components as illustrated.Moreover, some components may be substituted by other components.

Moreover, in the above-described example embodiment, description hasbeen given on specific configurations and operations of the pixelcircuit 101. However, configurations of the pixel circuit for activematrix driving are not limited to as exemplified in the above-describedexample embodiment. A capacitor or a transistor may be added asnecessary, or the connection relation may be altered. In this case,according to changes or alterations of the pixel circuit, an additionaldrive circuit may be provided in addition to the above-mentioned drivesection (the signal selector 103, the main scanner 104, and the powerscanner 105). Moreover, it goes without saying that driving methods andoperations of the pixel circuit are not limited to as exemplified above,but appropriate changes or alterations may be possible.

Furthermore, a material and a thickness, or a deposition method or adeposition condition of each layer as described in the above-mentionedexample embodiment are not limited to as exemplified above, but othermaterials and other thicknesses, or other deposition methods or otherdeposition conditions may be adopted.

In addition, in the above-described example embodiment, description hasbeen given on a solid sealing structure in which the display element 20is covered with the protective layer 25, the adhesive layer 26, and thesealing substrate 27, with no space left between the protective layer 25and the sealing substrate 27. However, it is possible to adopt a hollowsealing structure in which the display element 20 is covered with theprotective layer 25 and a lid member (not illustrated), with a spaceleft between the protective layer 25 and the lid member. In this case,it is desirable that a getter agent (not illustrated) is disposed in thespace between the protective layer 25 and the lid member, preventingwater from intruding into the organic layer 23.

Furthermore, in the above-described example embodiment, description hasbeen given on a case that the display element 20 includes the anodeelectrode 21, the organic layer 23, and the cathode electrode 24 in thisorder from the base 11 side. However, the anode electrode 21 and thecathode electrode 24 may be inverted, and the display element 20 mayinclude the cathode electrode 24, the organic layer 23, and the anodeelectrode 21 from the base 11 side. Also in this case, it is possible toadopt both the upper surface emission in which light is extracted fromthe anode electrode 21 side and the lower surface emission in whichlight is extracted from the cathode electrode 24 (the base 11) side.

Further in addition, in the above-described example embodiment,description has been given on specific configurations of the displayelements 20, 80, and 90. However, it is not necessary to include all thelayers, and another layer or other layers may be further provided.

Furthermore, the display elements 20, 80, and 90 may be configured ofother display elements such as an inorganic electroluminescence element,or an electrodeposition or electrochromic display element or the like,in addition to the organic EL element, the liquid crystal displayelement, and the electrophoretic display element.

It is to be noted that effects described in the specification are merelyexemplified and not limitative, and effects of the present disclosuremay be other effects or may further include other effects.

It is possible to achieve at least the following configurations from theabove-described example embodiments of the disclosure.

-   (1) A thin film transistor, including:

a base that includes, on an upper surface, a first region and a secondregion other than the first region;

a gate electrode that is provided on the first region of the base;

a gate insulating film that is provided on a surface of the gateelectrode and the second region of the base; and

a semiconductor layer that is provided on a surface of the gateinsulating film,

wherein the semiconductor layer includes a third region and a fourthregion other than the third region,

in the third region, the semiconductor layer and the gate electrode facewith a minimum interval,

in the fourth region, a distance from the semiconductor layer to thegate electrode is larger than the minimum interval, and

at a boundary position between the third region and the fourth region,the semiconductor layer forms a linear shape or a substantially linearshape.

-   (2) The thin film transistor according to (1), wherein

the base includes, in the second region, a fifth region and a sixthregion, the fifth region being inclined with respect to the firstregion, the sixth region being parallel to the first region, and

the boundary position between the third region and the fourth region ofthe semiconductor layer is different from a position at which thesemiconductor layer bends in shape at a boundary between the fifthregion and the sixth region of the base.

-   (3) The thin film transistor according to (2), wherein

the gate electrode includes an upper surface and a side surface, theupper surface being parallel to the first region, the side surface beinginclined with respect to the first region, and

the side surface of the gate electrode and the fifth region form alinear shape or a substantially linear shape.

-   (4) The thin film transistor according to (2) or (3),

wherein a level difference between the first region and the sixth regionof the base is larger than a thickness of the gate electrode.

-   (5) The thin film transistor according to any one of (2) to (4),    wherein

the base is configured of a laminated body of a first insulating layerand a second insulating layer,

the first region has a configuration in which the second insulatinglayer is laminated on the first insulating layer,

the fifth region is configured of a side surface of the secondinsulating layer, and

the sixth region is configured of an upper surface of the firstinsulating layer.

-   (6) The thin film transistor according to any one of (2) to (5),

wherein the fifth region is provided on one or both of a drain side anda source side of the gate electrode.

-   (7) The thin film transistor according to (1),

wherein the semiconductor layer has a linear shape that is parallel tothe first region.

-   (8) The thin film transistor according to (1), wherein

the gate electrode has an upper surface and a side surface, the uppersurface being parallel to the first region, the side surface beinginclined with respect to the first region, and

a degree of inclination of the semiconductor layer with respect to thefirst region at the side surface of the gate electrode is different froma degree of inclination of the side surface of the gate electrode withrespect to the first region.

-   (9) The thin film transistor according to (8), further including a    side wall, the side wall being provided on the side surface of the    gate electrode.-   (10) A display device provided with a display element and a thin    film transistor that is configured to drive the display element, the    thin film transistor including:

a base that includes, on an upper surface, a first region and a secondregion other than the first region;

a gate electrode that is provided on the first region of the base;

a gate insulating film that is provided on a surface of the gateelectrode and the second region of the base; and

a semiconductor layer that is provided on a surface of the gateinsulating film,

wherein the semiconductor layer includes a third region and a fourthregion other than the third region,

in the third region, the semiconductor layer and the gate electrode facewith a minimum interval,

in the fourth region, a distance from the semiconductor layer to thegate electrode is larger than the minimum interval, and

at a boundary position between the third region and the fourth region,the semiconductor layer forms a linear shape or a substantially linearshape.

-   (11) An electronic apparatus provided with a display device, the    display device including a display element and a thin film    transistor that is configured to drive the display element, the thin    film transistor including:

a base that includes, on an upper surface, a first region and a secondregion other than the first region;

a gate electrode that is provided on the first region of the base;

a gate insulating film that is provided on a surface of the gateelectrode and the second region of the base; and

a semiconductor layer that is provided on a surface of the gateinsulating film,

wherein the semiconductor layer includes a third region and a fourthregion other than the third region,

in the third region, the semiconductor layer and the gate electrode facewith a minimum interval,

in the fourth region, a distance from the semiconductor layer to thegate electrode is larger than the minimum interval, and

at a boundary position between the third region and the fourth region,the semiconductor layer forms a linear shape or a substantially linearshape.

-   (12) A method of manufacturing a thin film transistor, the method    including:

forming a gate electrode on a first region of a base, the baseincluding, on an upper surface, the first region and a second regionother than the first region;

forming a gate insulating film on a surface of the gate electrode andthe second region of the base; and

forming a semiconductor layer on a surface of the gate insulating film,

wherein the semiconductor layer includes a third region and a fourthregion other than the third region,

in the third region, the semiconductor layer and the gate electrode facewith a minimum interval,

in the fourth region, a distance from the semiconductor layer to thegate electrode is larger than the minimum interval, and

at a boundary position between the third region and the fourth region,the semiconductor layer forms a linear shape or a substantially linearshape.

-   (13) The method of manufacturing the thin film transistor according    (12), further including, after forming the gate electrode, etching    the second region of the base using, as a mask, the gate electrode    or a resist film having a same layout as the gate electrode, to form    a fifth region and a sixth region in the second region, the fifth    region being inclined with respect to the first region, the sixth    region being parallel to the first region,

wherein the boundary position between the third region and the fourthregion of the semiconductor layer is different from a position at whichthe semiconductor layer bends in shape at a boundary between the fifthregion and the sixth region of the base.

-   (14) The method of manufacturing the thin film transistor according    to (13), wherein

in forming the gate electrode, the gate electrode is provided with anupper surface and a side surface, the upper surface being parallel tothe first region, the side surface being inclined with respect to thefirst region, and

in etching the second region of the base, the side surface of the gateelectrode and the fifth region form a linear shape or a substantiallylinear shape.

-   (15) The method of manufacturing the thin film transistor according    to (13),

wherein in etching the second region of the base, the second region ofthe base is etched deeper than a thickness of the gate electrode.

-   (16) The method of manufacturing the thin film transistor according    to (13), wherein

the base is configured of a laminated body of a first insulating layerand a second insulating layer, and

in etching the second region of the base, the second insulating layer ofthe sixth region is removed.

-   (17) The method of manufacturing the thin film transistor according    to (12), wherein

in forming the gate electrode, a spacer layer is formed in the secondregion, the spacer layer having a same thickness or a substantially samethickness as a thickness of the gate electrode, and

in forming the gate insulating film, the gate insulating film is formedon an upper surface of the gate electrode and an upper surface of thespacer layer, allowing an upper surface of the gate insulating film tobe formed flat.

-   (18) The method of manufacturing the thin film transistor according    to (12), further including, after forming the gate electrode,    forming a side wall on a side surface of the gate electrode,

wherein a degree of inclination of the semiconductor layer with respectto the first region at the side surface of the gate electrode isdifferent from a degree of inclination of the side surface of the gateelectrode with respect to the first region.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A display device comprising: an insulatingsubstrate; an electrode disposed on the insulating substrate; aninsulating layer disposed on the electrode; and a semiconductor layerdisposed on the insulating layer, a surface of the semiconductor layerincluding a first corner, a second corner, a third corner, and a fourthcorner in a cross-sectional perspective, including a first horizontalregion extending from the first corner and a second horizontal regionextending from the fourth corner, and including a first slope regionextending from the first corner to the second corner and a second sloperegion extending from the third corner to the fourth corner, wherein thefirst slope region and the second slope region are disposed between thefirst horizontal region and the second horizontal region, the firstcorner, the second corner, the third corner, and the fourth corner aredisposed outside of a region overlapping with the electrode in a planview perspective, the semiconductor layer includes a channel region of adrive transistor, the channel region disposed between the first sloperegion and the second slope region, the drive transistor beingconfigured to supply a drive current to a light emitting element of apixel, the first slope region has a first angle with respect to asurface of the insulating substrate, a side surface of the electrode hasa fifth corner, a sixth corner, a seventh corner, and an eighth cornerin the cross-sectional perspective, and including a third slope regionextending from the fifth corner to the sixth corner and a fourth sloperegion extending from the seventh corner to the eighth corner, the thirdslope region has a second angle with respect to the surface of theinsulating substrate, the first angle is smaller than the second angle,and the second angle is greater than zero degrees and less than ninetydegrees.
 2. The display device according to claim 1, wherein a minimumdistance between the first corner and the fifth corner is shorter than aminimum distance between the second corner and the sixth corner.
 3. Thedisplay device according to claim 1, wherein the electrode is set to apredetermined potential.
 4. The display device according to claim 3,wherein the electrode includes aluminum, titanium, copper, molybdenum,or a combination thereof.
 5. The display device according to claim 3,wherein the insulating substrate is a plastic film.
 6. The displaydevice according to claim 3, wherein the electrode is a gate electrode.7. The display device according to claim 1, wherein the light emittingelement of the pixel is configured to emit a white light.
 8. The displaydevice according to claim 7, further comprising a side wall, wherein anedge of the electrode is covered with the side wall.